Climate change predictions suggest Britain will increasingly see periods of both drought and flooding in the future and while better drainage provides the answer to too much rain, rain water harvesting could offer the solution to too little.
It is an idea which has much to recommend it, both practically and from the point of view of sustainability. In the UK, all the water in our mains supply has been treated to drinkable standards – but we actually drink very little of it.
Leaving aside the ethics of using such a precious resource to wash your car, when so much of the developing world draws its supply from muddy and contaminated sources, it is clearly a very inefficient use of energy to clean water to such a high standard, and then flush it down the drain.
There are many purposes for which rain water is perfectly adequate and for parts of the country where water metering is already in place, it has the added benefit of arriving freely – and at times in quite large volumes!
Low Cost Collection
One of the most effective ways to get started involves that old garden favourite – the water butt. Add one of these to an available down-pipe and for a very modest investment you have a free supply of water for watering the garden or washing the car.
For bigger gardens, there are kits available that let you fix two or three butts together to collect even more, with a cleverly designed overflow valve making sure that they fill up in sequence and a diverter pipe to attach to your down-pipe to ensure that they don’t overflow.
This simple approach to rain water collection makes an ideal subject for a campaign, largely because it’s a very familiar idea and the costs involved are fairly small. If the idea takes off well enough, it might even be worth approaching suppliers or manufacturers of water butts and kits to see if they could offer a discount for bulk buying.
A community project can often benefit from the purchasing power offered by a relatively large number of individuals and many companies see being involved in high-profile schemes as good PR, so it’s worth asking. The added publicity can also benefit the campaign too and help you get your message across.
However, if you want to take the idea further, then large scale rain water harvesting offers the possibility of providing your own supply for a range of uses which don’t require the purity of drinking water – including flushing toilets or doing the washing. Roof top systems of this kind don’t come cheap, though.
As a rough guide, to provide a suitable rain water harvesting installation to the meet the toilet flushing needs of the typical three or four bedroom house, you will be looking at between £1,000 and £2,000, depending on the equipment used.
Of course, at this sort of size, the whole thing is a little more complicated than a butt attached to your drainpipe. There is usually a large underground storage tank with a filter system and some also have an ultra violet (UV) system to help disinfect the water before use. Many installations also have control mechanisms so that if the level drops too low, it switches over to mains or if the tank is full, the excess is safely diverted to a drain.
Large rain water harvesting systems can reduce the use of mains water by 30 per cent and even exceptionally as much 50 per cent. However, at a cost of perhaps £2,000 – £3,000, even with metered water, the pay-back period is likely to be very long – so it’s probably something to consider more for its “green” merits than its potential money-saving benefit.
If British summers are going to become drier – except when the heavens do open and we risk being flooded – then water is something we’re all going to have to stop taking quite so much for granted. Whether you’re looking to be more sustainable and ethical in the way you use water – or just want to be able to water your plants, rain water collection is certainly something to think about.