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  • HPH373: Using a willow bed to treat sewage – with Laila Dudhill

    HPH373: Using a willow bed to treat sewage – with Laila Dudhill

    Laila Dudhill explains some of the challenges she faced when planning her new build home at the bottom of a sloping field. Not only did she have to deal with drainage across the site, diverting the natural flow of water away from the house, but also come up with a foul drainage strategy that would off-set phosphate discharge into the local watercourses.

    Interview with Laila Dudhill

    Laila Dudhill has a 40-acre farm in Herefordshire, in one of the river catchment areas in the county that is sensitive to phosphate pollution. Her land is partly situated on heavy clay and on a gradient, so a lot of thought has had to go into dealing with all aspects of water run off and foul water treatment. In the early stages of planning her project she developed rheumatoid arthritis, which increased her determination to step away from the responsibilities of the farm and influenced her designs for the new house.

    The original barn and field

    ‘Class Q’ permitted development allows for a change of use

    Class Q planning permission allows for a change of use from agricultural buildings to residential dwellings. Laila’s barn was a 1990s steel frame structure and the Class Q permitted development allowed her to build to the same footprint, same envelope and same size. The steel frame was a problem for Laila as the steels would have created thermal bridging and heat loss. This meant she had to go back to the Local Authority after receiving Class Q permission and gain consent to replace the steels (in other words, build new). She also needed to alter the angle of the roof slightly so that it would be optimised for solar PV. This resulted in the pitch being slightly higher than the original barn.

    The old barn is dismantled

    Any new home must address phosphate pollution

    Herefordshire has a large number of intensive poultry units, which has resulted in high phosphate levels in the River Wye and the River Lugg. The Council is concerned about more phosphates coming from the foul drainage of new properties, so every planning application in this area must demonstrate what measures will offset the phosphates.

    There are ways to off-set phosphate discharge

    Laila explains that her foul drainage strategy will double the offset requirement. Her main system is a willow bed and a septic tank, rather than the more common biodigesters. A biodigester requires a large drainage field, which was a problem for Laila being on heavy clay soil. It also cleans the effluent much better than a septic tank, so wouldn’t provide enough nutrients for a willow bed. 

    The willow bed satisfied her planning requirements, but Laila has been able to continue to add to her phosphate off-setting in various ways. Taking agriculture off the land gives you a phosphate credit along with planting trees, particularly fruit and walnut trees.

    The contours of the land and the flow of water

    The natural water flow was straight past the barn

    The site’s drainage has been of particular concern

    Topographical surveys and drainage studies were carried out, including percolation tests to determine the speed water drained through the ground. The field in front of the house was clay, with very poor drainage, whilst the woodland at the back had extremely fast drainage. Neither situation is good for a drainage field. Either the water sits on top of the soil with potential run-off to the watercourse or it goes through the soils so fast that the nutrients aren’t retained in the soil. The septic tank and willow bed will retain all nutrients from her foul water system, with periodic de-sludging of the tank required.

    Having lived on the site since 2006, Laila had a good knowledge of how water flowed through the site to a pre-existing pond (that’s shown on Ordnance Survey maps). She tells us about springs that issue from within the woods, but that she had not experienced any flooding around the barn until last winter, which was then repeated this year. She is not in a flood zone and believes this is because she is on a slope, so water doesn’t rise around the property but flows past in extreme weather. A new flood alleviation pond has been created to hold excess surface water and the recent severe weather tested the system and showed that some adjustments were needed.

    A flood alleviation pond was dug

    Water is piped from the flood alleviation pond under Laila’s driveway, to the head of a brook that emanates at the edge of the woodland and also picks up the woodland springs. Water from the brook eventually feeds into the River Arrow within the Lugg catchment which is why the foul drainage from the house needs to be managed separately to the rest of the surface water run-off.  The rain water which falls on the house can simply be discharged into a free draining area of the woodland.

    Digging the giant willow bed

    Lining the willow bed

    Back-filling the willow bed

    The willow bed is an effective way to treat the sewage

    From the house, all the sewage goes into a septic tank, which links into a willow bed. This is lined so nothing can escape into the surrounding soil. The bed is backfilled with soil and planted with willow, which uses the water from the foul drainage in transpiration and uses the nutrients to grow. Laila is researching which varieties to grow, how close to plant them and how often they should be coppiced so that people will want to use the willow.

    The willow bed requires a lot of space

    Laila’s drainage consultant Alan Corner looked at a Danish study and an Irish study to work out how big the willow bed needed to be. The specification is based on the number of bedrooms in a house, as that generally determines occupancy. Strictly speaking, Laila’s is a four bedroom house, although she will usually be living there on her own. The specification for the willow bed has come out at 47 metres by 8 metres, about the size of an Olympic swimming pool!

    “I’ve coined a phrase, I’m going to grow a crop from my crap”

    Financially, it’s been expensive and probably it would not be an option for most people, but Laila says it was a really interesting process and a good test case.

    Get recommendations when building up your team

    Laila tells us that she has found the whole process positive, with one thing organically leading to another and people always happy to explain things and answer questions. Initially she had a recommendation for a planning consultant, who then guided her through the planning application process and put her in touch with a groundworker. She interviewed a few architects and selected one.

    Building a house can be stressful

    Even when people are fantastic and things are exciting, Laila points out there is still stress, which is not ideal for her rheumatoid arthritis. But she has support from her rheumatology team, who try to keep her condition tolerable.

    Dividing the farm has helped finance the new home

    Laila feels fortunate that her farm can be divided quite nicely into two (by the main road), so she can sell the farmhouse, land and outbuildings on one side, whilst keeping the rest for her new home. She is currently still living in the farmhouse, but will need the sale to go through in order to complete the build.

    Embracing simplicity makes it easier to build and achieve the Passivhaus standard

    Laila’s father was an engineer and her mother was a mathematician, and so Laila understands the benefits of keeping things simple. Passivhaus Consultant Nick Grant has been advising and she has been happy to implement all his recommendations. This ultimately leads to doing more with less.

    The foundations for the new home are dug

    The binding layer of the foundations

    The foundations are nearly complete

    The groundworks and Isoquick base are now complete

    Laila’s structural engineer was happy that the stony ground the original barn was sitting on was sound for an Isoquick insulated raft foundation. The site was excavated down to around 750mm below the finished floor level and then built up with a sub-base material, which was compacted, and a final 50mm fine drainage stone to create a flat surface. The Isoquick raft sits on top of this followed by a layer of concrete, so they are ready for the superstructure.

    We will revisit Laila later in her build to hear the next steps in her journey.

    Find out more

    The Passive House Builder

    Corner Water Consulting

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  • HPH296 : How to connect a new water supply to your home – with John Hernon from Thames Water

    HPH296 : How to connect a new water supply to your home – with John Hernon from Thames Water

    John Hernon from Thames Water explains the process of installing a new connection to a water main. He also outlines the role of water services company that delivers clean water and takes away waste water.

    Interview with John Hernon

    John is a strategic development manager for Thames Water. He has been working in the business for nearly 20 years, with much of that time spent dealing with developers and working on connections.

    Thames Water provides clean and waste-water to millions of customers

    Thames Water is the largest of the water companies in the United Kingdom, with 9 million clean-water customers, and around 50 million waste-water customers. Their role is to provide clean water to households, and take their waste away.

    They have a network of over 30,000 kilometres to service and maintain, made up of the strategic network, which is the massive pipes that transport water across the region, and the local distribution network.

    They also have 350 sewage treatment works. Once the sewage has been collected through the network, it has to be treated to a stage where it can be put back into the water course.

    Solids are separated from liquids before being dried, with some of the by-products being sold on to farmers. Liquids go through a process of treatment and screening before being put back out into the environment.

    Much of the network is over 100 years old

    Being such an aged network, much of it is made up of cast iron pipes. There is a massive project underway to replace and upgrade the aging network, but as this brings about inevitable disruption, it has to be managed carefully.

    Booster stations help control water pressure

    Providing clean water uses a pressurised system in order to guarantee a certain amount of pressure to each customer. And where gravity can’t be used, such as when water needs to be taken to properties on a hill, booster stations can boost that supply.

    The guaranteed minimum at the boundary of a property is 1 bar of pressure, but much of the network operates at a higher pressure. One bar of pressure is, if you were to put a nail through that water main, water would spray ten metres in the air.

    Contact them as early as possible

    John suggests that anyone wanting a new connection, whether for a large or small development, should get in contact with them as soon as possible, and ideally even before the planning stage.

    “By getting early visibility and someone saying, ‘we want to build a new house and it’s somewhere where we haven’t got a water network’, we might have to do significant reinforcement to our mains network to supply that. So, we would want to speak to that person as soon as possible to understand the constraints that we need to face and whether we’d need to cross a third party’s land and so on.”

    He says there’s usually a solution, but it can get costly if the new build is in a remote area which has a long run to the nearest connection point. Their pre-development process can offer the customer an estimate about what they’ll need to do to their network, even before it goes for planning approval, so it’s always advisable to get in touch early.

    John says that Thames Water have upgraded their website with a focus on their single-build / smaller customers to try and help them through what could be a confusing process for a novice.

    Once an application has been received, a quotation will be sent out within 14 days. When the quote has been paid it will be valid for 180 days.

    Things that will impact on the cost will be the distance from their nearest assets, any traffic management, lane rental charges etc.

    The most significant thing to potentially impact on the schedule is local authority restrictions, which is why it’s so important to contact the water company as soon as possible. Digging up a road can cause disruption and traffic management problems, so balancing the needs of the customer with local authority requirements can take a number of weeks to resolve.

    Their responsibility is to provide the water supply to the boundary

    Once the supply has been installed, their responsibility continues to that customer. They have to ensure that the meter is installed and logged onto their network and that the account is setup so the customer can be charged for the services. They also have a duty of care to ensure that what has been built and connected to the water network is fully compliant, and will carry out inspections to make sure it is.

    The self-builder should appoint an approved plumber

    This plumber will run the pipework from the inside stop valve out to the boundary. They would need to lay a run of 25mm or 32mm pipework out to the boundary, at a depth of one metre, and leave a little extra pipe there. This helps with frost protection and summer heat gain, and will enable them to link up with the existing assets in the street.

    Thames Water would then carry out an inspection to make sure it is to the right location and using the right material. Occasionally a protective pipe / barrier supply will be needed if it is deemed to be in a contaminated area, but ideally the pipes are just laid onto the soil without sleeves. Sleeves could hamper the chances of identifying a leak if there was an issue.

    The meter will generally be installed at the boundary in the footpath. This clearly marks the point at which Thames Water’s responsibility ends and the customer’s begins.

    Thames Water and their contractors would then take over and liaise with the highway authority, to do the final connection of the pipework to the main in the street.

    Choose water-efficient products

    John recommends that people are careful about the products they buy, and consider that although cheap products might save money upfront, they may not actually be very water efficient. He uses the example of dual flush toilets, where a lot of the cheaper ones fail and end up wasting lots of water. He would encourage people to choose the most efficient products that will save water.

    He also advises people to be especially careful to avoid misconnections on the waste side of things. It’s important that the waste isn’t accidentally connected to a drain, which could potentially pollute a watercourse. In order to avoid this, consent from Thames Water to connect to their waste system must be obtained. They will arrange an inspection to make sure that a proper connection to the sewage system has been carried out.

    Thames Water have plans for improving the network

    John says that Thames Water are looking to install a network of smart meters across the region which will aid their understanding of what customers are using and where there are issues with supply. It could also identify a supply that’s running 24/7, which would mean there’s probably a leak somewhere between the meter and the property.

    They are also actively looking into ways of introducing grey water systems for flushing toilets, which don’t need to be done with the clean water they currently use.

    Most of the network across London is a combined network, which is where the rainwater and sewage are combined. This puts a lot of pressure on the aged network, because when there is heavy rain the sewers become inundated. So, they’re looking at how they might be able to separate the surface and foul networks to ensure that surface can be sent to a water course, and the foul can be taken back to the treatment works.

    Leakage is a big issue for Thames Water so they have set a massive target to deliver on within five years, to drive down the amount of water being wasted.

    And finally, improving the customer experience is a focus for the next five years too. There is work going on to upgrade their website so that if a customer has a query they should be able to find the answers online without having to join a queue in a call centre.

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  • HPH182 : Extracting energy from watercourses by generating electricity and extracting heat – with Justin Broadbent from ISO Energy

    HPH182 : Extracting energy from watercourses by generating electricity and extracting heat – with Justin Broadbent from ISO Energy

    Justin Broadbent from ISO Energy explains the options available for extracting energy from water on your plot of land.

    Interview with Justin Broadbent

    It’s our second chat with Justin Broadbent who is the chairman and founder of ISO Energy, a renewable energy installer. Last time he explained what a ground source heat pump is.

    Water gives more energy than wind because of its density

    There is a long history of using watercourses to drive mechanical objects in the UK. Although grain grinding was wind-powered, the mills of the early Industrial Revolution were driven by water because of the amount of power in it.

    Extracting heat from water can be simple and efficient

    If you have a small stream running through your garden, the simplest and most worthwhile thing you can do is extract energy in the form of heat. Justin says, “If you have the right spot and you have the right watercourse, then it is fantastic.”

    Any water can be used for energy extraction

    A large pond can be used for extracting heat; the amount of energy depends on the size of the pond and the heat load required. A flowing river has a constant temperature of 7 to 12 degrees, and a pond can get much warmer.

    If there’s a flow in and out of the pond, the energy is effectively being replaced all the time. With a stream, the energy is quickly replaced so more heat can be extracted.

    Choose the correct heat extraction device

    In a pond with fairly slow running water, Justin would install a simple mechanism that extracts heat using coils of plastic pipe.

    Lake ‘Loop Collector’

    In slightly flowing water he would use ‘Energy Blades’. These banks of stainless steel ‘radiators’ extract an enormous amount of energy. Justin explains, “Almost whatever you take out, as long as you don’t actually freeze the water, two seconds later, there’s new fresh water coming down the stream.” Such systems can be scaled up to extract hundreds of thousands of kilowatt-hours a year, by putting in banks of multiple radiators.

    Installing Energy Blades

    Energy Blades in action

    You may need planning permission

    In an area of outstanding natural beauty you must obtain planning permission for works like these. Additionally, Justin says you would need permission from the Environment Agency to dam a river or stream, but not if you wanted to put an Energy Blade in the water as it’s easily removable.

    Expertise is necessary but installation is relatively straightforward

    Justin says that extracting heat from water is cheaper and more efficient than from the ground, which is not as straightforward. He says it’s worth employing professionals but essentially, if you’re fortunate enough to have a stream, you can easily install an Energy Blade for two to three thousand pounds. To do the same in the ground, he estimates a cost of five or six thousand pounds.

    Heat extraction doesn’t have to be hugely invasive

    Some of Justin’s clients make a feature of how they’re heating their house, for example diverting part of their stream, and adding a canal and viewing walkway. But you can simply put the energy blade in the stream and dig a small trench back to your heat pump.

    Hydroelectric generation ideally needs both volume and flow of water

    To generate electricity from water, you need the water to drop enough between the top and bottom of the stream. The greater this ‘flow’ or ‘head’, the more power you can generate. Justin summarises, “In an ideal world you have head and volume and then you can build a traditional turbine. If you don’t have the head, then you have to have even more volume.”

    Traditional hydro systems are built near big mountain rivers in places like the Alps, Scotland and Wales. The right features are not easily found in the south of England and where they do exist you’d be unlikely to get planning permission.

    If you can’t have a turbine, look for old water mills

    In Southern England, generating electricity from water is rare. However, Justin’s company has converted several mills where turbines can’t be used but the volume in the hill stream is sufficient to drive an ‘Archimedes Screw’, where the flow of water turns an electrical generator.

    Archimedes Screw in action

    The same feed-in tariff for photovoltaic cells applies to an Archimedes Screw

    Some of these systems generate a constant 15 to 20 kilowatts of electricity an hour. As this is far more than a single house needs, you can sell the surplus back to the electricity companies. Justin adds, “If you have photovoltaic panels on your roof, they might produce a few kilowatts. Well, an Archimedes Screw should be able to generate tens of kilowatts. Much more efficient.”

    These are low maintenance, robust systems

    Energy blades are fairly static and require very little maintenance. As they are stainless steel they don’t rust and have quite a long lifecycle. Furthermore, they are protected by guards built on the front.

    Likewise, Archimedes screw systems are heavy but fairly basic, just needing the bearings replaced when they eventually go and some maintenance of the gearbox.

    Environmental considerations can add costs

    Heat extraction in streams won’t affect wildlife, as the amount of energy taken out is so small in relation to the volumes involved. A pond cooling may affect wildlife slightly, but Justin is reassured that those species survive lower temperatures in Scotland.

    Justin explains that you can’t block a stream completely to use the power of the water. One common, though costly, method to ensure that fish, eels and animals can get by is to use a ‘fish pass’. A maze of gradual drops allows fish to swim upstream, avoiding the mechanism.

    You get less return on investment with a smaller system

    There’s not much difference in the cost of a small system producing five kilowatts and one giving 10 to 20 kilowatts of energy, because of the costs of getting permissions, civil engineering and manufacturing. Justin explains that his company rarely works on systems that are producing less than 20 kilowatts. “Suddenly you’ve found that it’s all going to cost £150,000 and you’re only going to make £5,000 a year out of it. It doesn’t pay back.”

    ItemApproximate Cost
    5 kilowatt Archimedes Screw £15,000
    20 kilowatt Archimedes Screw£60,000
    Civil engineering£20,000
    Fish pass£30,000
    Planning permission / consultant’s time£40,000

    It’s worth investigating how to use any water source on your plot

    You may be able to generate electricity or heat, or even both, from water on your land.

    With current government incentives (those for generating electricity normally last 20 years, and about seven years for heat), Justin calculates you can get your money back on a heat system within three to five years, followed by hugely reduced running costs.

    And you might even be able to get government incentives to support the construction of the system. “So, it’s definitely worth doing,” Justin says, “So long as the government grants are out there.”

     

    Find out more

    Visit the website of ISO Energy

    Follow ISO Energy on Twitter

     

    Transcript

    Download a transcript of the interview with Justin Broadbent

     

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  • HPH154 : The challenges of building a new home in a rural community – with Jeremy Harris

    HPH154 : The challenges of building a new home in a rural community – with Jeremy Harris

    Jeremy Harris, a scientist by background, wanted a low energy house for his retirement. He talks about the initial stages of his self-build project: finding a plot of land and obtaining planning approval.

    Jeremy Harris

    Interview with Jeremy Harris

    Jeremy Harris, a scientist by background, wanted a low energy house for his retirement. He first came up with the idea that he might like to build a house around ten years ago.

    It’s important to fully understand the beginning of the self-build process

    Jeremy found television programmes and magazines rarely touch on finding a plot, designing a house to fit that plot, and the people you have to employ to do all of that work. It can be very expensive, costing thousands of pounds for planning consultants, architects, building control, etc.

    Plots can seem very nice on websites but look nothing like the photographs in reality

    Finding a plot of land was extremely hard. The Harrises drove several thousand miles, visiting disappointing plots. They began by looking at what they wanted to build, but Jeremy concluded this was the wrong way round: first find a plot, then determine what type of house will fit on it.

    Having walked away from one likely prospect, by chance they found their plot of land 16 miles from where they were living. It was too overgrown to see properly and fenced so they couldn’t get into it, but looked like it might be exactly what they wanted: facing south (i.e. good solar access) and in a sheltered valley.

    There's a plot in there somewhere!
    There’s a plot in there somewhere!

    Buying a plot is not the same as buying a house – ensure services will be available

    When buying a plot of land a solicitor can tell you if there’s a public footpath on it but won’t find out if you’ve got water, mains electricity, mains sewage or even if the boundaries are in the right place.

    Services in rural areas are often stretched to the limit. Jeremy had to ask the relevant utility companies if they could supply:

    1. Electricity? Fortunately there was plenty of power on their doorstep.
    2. Water? Companies have a statutory duty to supply water but the issue is cost. They’d have to dig up a lane for 140 metres and although Jeremy shopped around (anybody with a licence can do the digging), the minimum cost was still £24,500.
    3. Mains sewerage? There’s no statutory requirement to supply this and the cheapest the water company could provide it was £14,800.
    4. A new phone connection? Telecoms companies see self-builders as developers. If there isn’t enough capacity, they can charge whatever they want to lay a new multi-cable.

    As services would cost so much, Jeremy renegotiated the price accepted. The land hadn’t sold for eight years so he persuaded the vendor to knock off a substantial amount.

    Many building plots have boundaries in the wrong place where the Land Registry is concerned

    Plots of land don’t have registered boundaries as a rule. There was a boundary error affecting the Harrises’ plot meaning the house approved to go on it wouldn’t fit.

    The process for resolving boundary errors is complex and time consuming. It’s up to the vendor to do it, so you have to persuade them to spend money with Land Registry to get title plans amended. This often affects adjacent houses, as well as your plot, involving lenders as they have a right on the title.

    A stumbling block can sometimes turn out to be an opportunity

    It took them a year to get their boundary error resolved, but this allowed time to plan the project properly.

    Jeremy wrote a brief with eight key design points but the architects he approached didn’t seem to understand the role of design with low energy houses. Looking further afield for a Passivhaus specialist was an option, but thinking the distance might make communication difficult Jeremy decided he’d design their house himself.

    So the year was productively spent:

    • Evolving designs for the house
    • Tracking down the local Openreach engineer who offered help at no cost, as Jeremy planned to dig trenches on the plot and an underground network would solve local problems with overhead cables and trees
    • Discovering a borehole was possible, at half the cost of mains water
    • Planning a sewage treatment plant, costing around £3,500; much cheaper than digging up the lane

    This avoided inflaming an existing situation with the neighbours, as the plot had a chequered planning history, and saved money too!

    The borehole
    The borehole

    Once the principle of development is established by an approval, it’s extremely difficult for planners to remove it

    The Harrises’ plot had planning permission for a little stone bungalow that they didn’t want. As the local authority had approved the principle of putting a house on the plot, their plan was to submit a new application.

    Areas of outstanding natural beauty, conservation areas and proximity to listed buildings put constraints on what you can build. For example, needing to have all the external materials approved, as was the case with Jeremy’s house.

    Good communication paves the way for a smoother planning application process

    In Jeremy’s area, seven objection letters result in the application being referred to a planning committee, where emotions come into play far more than planning law.

    A previous application for the plot resulted in 14 objections at Parish Council level and dozens of letters. To mitigate objections for their application, Jeremy spoke to every neighbour, sent them regular update newsletters and even Christmas cards.

    He also made scale models, enabling all interested parties to understand the design before the planning application went in. His wife could look inside the rooms to see whether they were big enough, and the neighbours could see what the house might look like in the landscape. And the scale model played an important part at the Parish Council planning meeting, where applicants aren’t allowed to talk.

    model-sw-view-small

    “We had several cases where objectors turned to supporters”

    Jeremy eliminated concerns by talking them through with neighbours:

    Genuine concernsWhat Jeremy did
    New house would overload the sewage systemExplained they were putting in a sewage treatment plant instead
    Height of the house might block views or cast shadowsUsed the 3D scale model to show that the house would be set into the hillside (3m down)
    Being overlooked in their back gardenUsed the model to show that the garage blocked the view (neighbour was also happy the garage protected their vegetable patch from the wind)

    Engaging with local people is important but Jeremy adds a caveat: be cautious and put your foot down if neighbours ask for too much; at the end of the day it’s your plot and your house.

    The Harrises got through the planning stage with no letters of objection at all, so the decision was down to a Planning Officer purely based on the law and planning policies for the area, and approval was granted.

    Transcript

    Download a transcript of the interview with Jeremy Harris

    Find out more

    Check out Jeremy’s blog on the project

     

    Please connect with me

     

  • HPH081 : Rainwater Harvesting From Your House – with Cath Hassell from ech2o consultants

    HPH081 : Rainwater Harvesting From Your House – with Cath Hassell from ech2o consultants

    Cath Hassell from ech2o consultants explains what rainwater harvesting is, why it’s useful and how to get started.

    If you haven’t heard our first podcast interview with Cath on the topic of saving water, check that one out first!

    cath-hassell

     

    Interview with Cath Hassell

    Rainwater harvesting is just one way of stopping rainwater from getting into our drains and sewers.

    If the house is in a city and rainwater is going into a combined sewer, then there will be more waste water to treat and there may be times when water treatment plants can’t cope and so the water spills out into local rivers or the sea.

    Keeping rain out of the stormwater stream reduces the likelihood of this occurring.

     

    What is Rainwater Harvesting?

    Rainwater harvesting is collecting rainwater that falls on the roof of a building. It’s taken from the roof because this is usually the cleanest water. This water is then stored outside but it can be used back in the building (for flushing the toilets, cleaning purposes, in washing machines, etc.) or it can be used outside the building for gardening.

    installing-a-rainwater-harvesting-tank

     

    Water is Stored Underground Because It’s Heavy

    There are two main reasons why water is stored underground:

    1. It’s heavy and therefore it does not want to be kept high up on top of a roof

    2. The water will be cool if stored underground reducing the risk of bacteria

     

    Water tanks can take up quite a lot of space so this might be another reason why it’s best to locate them underground.

     

    Setting Up Rainwater Harvesting is Easier for New Build

    In a new build house there is already going to be earth-moving equipment on site and so it becomes cheaper to dig a big hole.

    While it can be done in a retrofit situation, the initial set-up may cost more. There may also be issues such as no access to the back of a house (in a terrace, for example).

     

    Rainwater is Not Fit For Drinking or Bathing

    Astonishingly, in the UK, rainwater is actually given the same classification as water that has been swept from abattoir floors or contaminated with nuclear waste. For this reason there needs to be different pipework which runs to domestic taps, than for that which runs to toilets, washing machines etc.

     

    An Air Gap is Required to Prevent Water From Syphoning Back Into The Pipework

    The air gap is basically the space in between where the water can’t touch the taps. If a sink was overfilled the water would go down through the overflow or spill onto the floor and there would be no risk of the potentially dirty bathing water from re-entering the mains system through the taps.

     

    A High Carbon Load Damages The Reputation of Rainwater Harvesting

    The air gap does result in a loss of mains water pressure which can be overcome by pumping it to where it is needed, though using electrical pumping obviously does have a financial and carbon cost associated. The performance of the pumps can however be optimised by using particular valves.

    A high carbon load is one of the arguments that gets used against rainwater harvesting, but Cath would welcome research to be carried out looking at how taking rainwater out of the stormwater stream impacts on the reduced carbon load of the sewers and sewage treatment plants by reducing pumping there.

     

    Decisions About Rainwater Systems Can Influence The Designs of a New Building

    Cath suggests that if you’re planning a green roof she would not recommend rainwater harvesting for use back in the building. This is because the water run-off from the green roof will be discoloured and residents of the building may start using bleaches and cleaning products to remove the staining to their toilet pans.

    There is no reason why rainwater couldn’t be harvested by other areas of the building which do not have a green roof, and simply designed in with the gutters and downpipes.

     

    A Calculation Determines The Size of The Required Rainwater Storage Tank

    The storage tank holds approximately 5% of the anticipated rainwater that will be harvested in a year, which equates to around a 3 week supply. This is usually enough as the rain falls year round in the UK but there will still be some times where the tank will be too full or too empty. When empty the supply can be switched temporarily back to the mains, and when too full the overfill can be directed back towards the stormwater drains or into areas of garden that can cope with being inundated by water.

     

    Cath Has a Kickstarter Project to Produce a Book Designed to Help Educate Children

    A lot of Cath’s work is designing systems for schools. She has a Kickstarter project which will enable her to produce a book explaining about how the toilet systems work which she will be able to use when talking with the children.

     

    The Storage Tanks Are Generally Either Made of GRP (Glass Reinforced Polyester) or Polyethylene

    In the early days of rainwater harvesting the storage tanks tended to be made of concrete. Nowadays the two options are GRP (mostly for larger tanks) or poly (mostly for smaller tanks).

    A life cycle analysis was carried out on the two by Judith Thornton (CAT, AECB) who found that poly tanks were far better in terms of overall carbon footprint.

     

    Use Rainwater Harvesting Purely For The Garden if The Demand is Great Enough

    Cath recommends that for a domestic situation where you have a large requirement for garden watering, that you just use the rainwater for that and do not try and bring it into the house. Her reasons for this are because of the extra pipework and pump (for the mains backup) that will be needed. An additional outdoor mains tap will provide extra if required.

    If you’re harvesting rainwater purely for garden use then a different calculation for the storage tank is required. This reflects that as much water as possible will be collected during the non-growing months, in order to provide the best supply for the growing months.

     

     Find Out More

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  • HPH036 : How to Save Water in Your Home – with Cath Hassell from ech2o consultants

    Cath Hassell from ech2o consultants shares why saving water – particularly hot water – is something we should all be doing. She also explains how we can achieve this in our houses through a mixture of technical solutions and behaviour change.

    *A lot of the information in this episode is specific to the UK. This is because it became difficult to keep answering in general world terms because in each country it would be slightly different.*

     

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    Interview with Cath Hassell

    Cath Hassell got into plumbing by chance but once she did she soon began to find it very interesting. After being given a book on composting toilets she then got into the environmental aspects of plumbing and has never looked back.

     

    A Building Has 3 Types of Water to Deal With

    1. The water that comes into a building

    2. The water that goes out of a building

    3. The water that falls onto a building

    All these types of water need to be addressed.

    So for water coming into the building, first it will be used in some way. Either we will drink it, cook with it, use it to flush the loo, use it to shower with or fill the bath with it. After that, the foul water will have to be removed from the house and dealt with in some respect.

    For the rainwater that falls onto our buildings it can be collected, stored and used or – as happens often in The West – it can be fed into a drain.

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    Sewage treatment plant

    It Takes a Lot of Energy to Provide Clean Tap Water

    Once rain has fallen it needs to be stored. That water then has to be cleaned and pumped into our buildings. Once we’ve used it, it has to be taken away and cleaned again before it can be put back into the environment. We must realise that tapped water comes at an environmental cost.

    Hand washing dish or pouring glass with drink water

     

    Sustainable Water Supplies Get Replenished on a Regular Basis

    Cath explains how originally settlements grew up around rivers before there was the ability to move water. A lot of water is also stored in naturally-occurring underground reservoirs (usually permeable rock) – known as aquifers – which are at varying depths. A hand dug well is an example of tapping into a shallow aquifer but many are hundreds of metres deep.

    When it rains some aquifers or groundwater get recharged, which is part of a yearly cycle. In other parts of the world that is not the case. The Sahara Desert, for example, does have water many metres beneath it but this fossilised water would not be recharged if it were extracted.

    So when we’re using water we must think of using it in a sustainable way.

     

    We Only Drink About 1% of Our Tap Water

    The water that is piped into houses in The West is potable water or drinkable water quality. Despite this fact we only drink about 1% of it! We might be cooking with another 1-3% of it. So the bulk of it is used for bathing or flushing the loo.

     

    Reduce the Water Your Loo Uses With Dual Flush

    In the 1960s the first W.C. ‘maximum flush volume’ regulations were introduced (in the UK), allowing 15 litres. Through the years this has gradually been tightened and around the turn of the millennium it was reduced to a maximum flush volume of 6 litres.

    Now there are lots of toilets around that are duel flush so you can use 6 and 4 litre dual flush or even 4 and 2.5 litre duel flush. Most of the time we only have a wee and so we don’t actually need 6 litres to flush it away. These systems are much more efficient.

     

    It’s More Important to Save Hot Water Than Cold Water

    The carbon footprint of cold water in the UK has been worked out at 1.2 kWh of electrical energy which translates into about 0.7kg of CO2 for every 1 m3. That takes into account the water coming into the house and then once it’s been used, the water being taken away and cleaned.

    As soon as water is heated the carbon footprint increases rapidly. Most of the time we’re using fossil fuels to heat water, which in turn is producing CO2 emissions. It is at this point that it becomes a global issue.

    It is estimated that 6% of the UK’s carbon footprint comes just from hot water we use in our homes!

    So there is an added benefit of saving hot water over cold water.

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    Not All Technological Advances Have Been Good!

    While W.C. flush regulations have become more stringent in terms of saving water, some technological solutions have almost gone the other way. Cath says that historically the UK has had very poor quality showers with low flow rates but that’s been changing. Having a combi boiler or a power shower means that flow rates have actually been going up.

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    Behaviour Change is Part of the Solution

    Technological solutions alone will not make significant strides in saving water: it must be combined with behaviour change. The key area we need to think about is taking a bath or having a shower.

    Cath says: “Are you under the shower to wash and get clean? Or are you under the shower to solve the problems of the world!”

    The average person in the UK uses 150 litres of water a day. A bath filled right to the top might be 160 litres of water and so would be using more than the average in one go.

    Depending on the flow rate of a shower, a 5-minute shower might use between 35 and 100 litres. That means a 20-minute power shower would use around 400 litres of water!

    Cath stresses how shorter showers and shallower baths can make a massive difference.

     

    Universal Metering Could Lead to a Fairer System

    60% of people in the UK still pay a flat rate for their water, regardless of how much they use, but that is gradually changing. As more and more meters are installed people will have to pay for water per volumetric.

    Cath believes this would be much fairer and she also proposes that there could be a base rate allowance of 150 litres per day (ideally 130 litres a day) above which there would be a premium. This would not stop people from taking deep baths or watering their gardens but would mean they pay more for the privilege.

     

    The Cost of Water Varies According to Where You Live

    There is not a universal price for water. Cath illustrates with a quick comparison. Those in the Thames Water area (London, Oxford, Reading, etc.) currently pay £2 per cubic metre of water as opposed to £5.50 per cubic metre of water for those that live in parts of the West Country (Cornwall, Devon, etc.).

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    Inside a flow regulator

    Flow Regulation Allows You to Set the Flow Rate of Taps, etc.

    When Ben suggests that flow regulation is about limiting water flow, Cath says that it’s more about setting the rate at which water comes out. Using a flow regulator does not mean that taps just dribble! You won’t even notice. It’s about being intentional.

     

    In the UK, There Are Benefits of Keeping Rainwater Out of the Storm Water Stream

    While it is possible to collect rainwater and use it in our buildings (for flushing toilets, in washing machines, etc.) Cath believes it would be far better – and much simpler – to use it in our gardens (assuming you have one!). This is because one of the big problems in the UK, particularly in cities, is that there are combined drains. So the foul water sewage is mixed with the rainwater. When there’s a lot of rain, the system cannot cope because there’s too much to process at the sewage treatment plants, which means the overflow mechanism is channelling it into rivers or the sea!

    Keeping rainwater by our houses – by use of a rain garden – would make it possible for our sewage treatment plants to clean all waste water.

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    A rain garden

    Rain Gardens Let Plants Do the Work

    A rain garden is an area that allows rain that might land on impervious surfaces the chance to be absorbed into the ground. It is planted out carefully to have maximum impact because on occasions it is going to be inundated with water.

     

    Cath’s Tips for Self Builders

    • Either put in an unvented hot water cylinder or a combi boiler so that the mains water is coming in at high pressure. Then use flow regulation. In Cath’s house her kitchen taps are set to 6 litres a minute and her wash basin taps to 4 litres a minutes, while the shower is 7.5 litres per minute.
    • Stay with a standard sized bath because most people like to relax in a bath sometimes and it can defeat the point in a smaller bath. However, become more intentional about using it (as described above).
    • If you’ve got a garden, collect as much rainwater as you can for use in the garden. Consider not connecting any of your rainwater downpipes into the drains. Use that water in your garden instead.
    • Avoid laying down any impermeable surfaces (such as big areas of concrete).
    • Look at using grey water – the water from showers and hand basins – in the garden at certain times of the year. Cath does this in the spring and the summer in her garden. They don’t bring grey water back into the house though.
    • Get a shower timer so that you can see how long you’re spending in the shower! A lot of water companies give these away for free.

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    A Year of Showering Variously

    Check out Cath’s blog on showering! As she travels around Cath is always taking notes. Perhaps she’ll be coming to a shower near you!

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    Transcript

    Download a transcript of the interview with Cath Hassell.

     

    Typhoon Haiyan

    With possibly the strongest winds ever to make landfall, Typhoon Haiyan killed thousands when it struck the Philippines on 8th November. Is this typhoon an anomaly or a sign of the more fierce weather that will become the norm? Ben talks about seeing the devastation of a minor typhoon when he visited Legaspi in 2006. Are these areas going to be uninhabitable if extreme weather like this continues?

    If you haven’t had a chance to donate, the Philippine Red Cross carries out some amazing work.

     

    Our Question for the Comments Section

    How have you reduced the amount of water that you use?

     

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