How we’ve cut water use in our home

 

As droughts look set to become a regular feature of life in the south-east, TTL’s Ann Link gives a tour through the water-saving features she and her partner have introduced to their Lewes home.

Collecting rainwater from our roof

We live in a chalet-style 1950s house in what has been described as the suburbs of Lewes. The good news is that means there are lots of sloping sections of roof collecting a huge amount of water, even in dry Sussex. We estimated in 2009 that ours would collect 11,000 litres of rainwater in an average year. To calculate this, you work out the horizontal area under the roof, or part of roof. Our total is 142 square metres (the same as the footprint area of the house). Then if 1 centimetre (10mm) of rain falls, the roof collects 10 x 142 litres, i.e. 1,420 litres. If you are planning to install a tank, it will perhaps only collect water from half of the roof. The annual rainfall is 782mm, or 78cm. Our roof gets 1420 x 78 = 11,076 litres in an average year. One of our roofs gets 5,300 litres on average.

So the potential for rainwater collection is enormous – it dwarfs the capacity of ordinary waterbutts. So it is worth getting larger tanks.

Using rainwater for toilets

We installed a rainwater collection system in 2009, mainly to feed our loos. Since then we have also added large tanks in the garden for watering.

The system for the loos consists of two 1,000 litre ex-juice containers, in a wooden housing outside, with an underwater pump to get the water up to a header tank in the loft. The internal piping and header tank in the loft have been done with the Rain Director system, with an electronic control panel in the bathroom cupboard. This has vastly reduced our water use, but there have been problems: two pumps failed, but the third is fine. You can see the model we now use here:

We think problems arose because our roof produces lots of sandy sediment. The present pump takes in water from nearer to the surface. The Rain Director prioritises ensuring we reliably have water in our cisterns, so it has various complicated features we don’t need. The pump power is around 800 watts. It probably uses more energy than Southern Water uses to give us the equivalent amount of water, although we often don’t notice because it is covered by our solar panel electricity, and it is not on very often. We can also draw water from the tank for watering the garden.

Using rainwater for the garden

Using large tanks for garden watering, which need not require pumping, is definitely a good thing! Because these are more visible, we have bought new tanks. These are fed directly from the gutters and downpipes. We have an 800 litre tank, a 750 litre, and two around 400 litres. At the time of writing they are all nearly empty and we have been using washing-up water like everyone else. In future years I shall conserve water used in the home more carefully.

Estimating our water usage

Our water consumption from the mains is around 24 cubic metres a year, or around 72 litres a day, which still seems quite a lot. We are generally careful, taking showers not baths, and saving water that we have to run in order to get hot water in taps, for example. We save this water for reuse. Because of long pipe runs, this can be about three litres. The loos are both geared to use less water and provide a small flush. We hardly ever water the garden from the mains. The main big reduction is from the rainwater feed to the loos, although I can’t be sure how much this is. If we have run out of rainwater during one of the six-month billing periods, it shows as roughly another 3 cubic metres. These periods don’t usually last long, and our two cubic metre tanks are full now after the recent couple of centimetres of welcome rain, as are all the garden tanks.

Estimating the cost savings

It’s hard to calculate exactly what savings we’ve made on water costs from our measures (and of course you have to factor in the cost of equipment and materials – and installation if you get someone else to do it for you).

We do of course have a water meter in order to try to benefit from our lower water usage (including other actions like only taking short showers and washing the car once a year). A quick bit of research using Southern Water data indicates that a typical household with two people using 274 litres will pay £1.52 per day for their water usage. We pay about 40p a day. The corresponding annual figures are £146 for us and £409 for the average two-person household. Southern Water’s figures include the charges for sewage, which are based (via a set formula) on water usage. Standing charges for each are included.  So we estimate we are saving over £260 a year, which I find quite surprising as it’s easy once the equipment is in place and shows how we can put less stress on our drought-threatened aquifers and rivers.

Stockists for tanks and water butts

The two tanks we got in 2009 are ex-juice containers, each 1,000 litres in volume, from D&V Fuels in Wrexham, N. Wales. The cost was around £140 for two, plus carriage, at that time. These are still available here. They are cheaper than the new purpose-made tanks. They need protection from UV light and possibly frost. We put some insulation in the wooden housing, which has leaked out but we have had no problem with freezing.

Another supplier (although one we haven’t tried) is https://shop.smithsofthedean.co.uk/ibc-tanks–containers-96-c.asp .

The newer tanks are from Etills. They are excellent and very tempting, but do involve a large amount of new plastic.

Recycled plastic butts are available, for example, from Even Greener. Their largest water butts are 350 litres but they can be linked together.

I am sure other people have better-planned systems and other ways of saving water. Please let us know what you are doing in the Comments below.