Rain Water Harvesting for a house extension - are they worth the trouble and cost in the UK?

Many would argue that fresh water is a very precious commodity that needs to be preserved and used carefully and I would tend to agree - if I was in Africa. However, the UK seems to be awash with the stuff so why should any householder consider installing rain water harvesting at extra expense when the stuff so readily flows out of the tap completely on demand throughout the year.

Even the odd drought conditions that happen every decade or so in the UK is more attributed with leaky distribution pipes and poor management, storage and servicing by the money grabbing water boards. So, should a householder who can afford the extra expense of rain water harvesting be considering the installation of a system for a house extension?

Well possibly yes but not for any ecological reasons. Quite simply the cost of mains water supplies are rising all the time and this is then fed back into the cost of sewerage charges in order to remove the waste water and treat it before discharging into the ground, river or at sea. So why use expensive and over priced drinking quality water to simply throw down the loo or sprinkle on the garden?

This could be similar to using sugar rather than salt to de-ice our roads. Does the same job but at 8 times the price. Therefore for adding in what is essentially a sealed plastic rain water collecting tank and a basic pump, rain water harvesting could be a very useful installation if only to reduce a homes water bills well into the future.

The complications of a fully functioning rain water harvesting system come later on when a distribution system has to be devised to get the rain water to where it can be utilised for the WC flushing and irrigation around the property. If the rain water is to be used for other areas such as for a washing machine then additional filtration or sanitation is usually required and it is often these extra complicated fittings and systems that tend to go wrong.

Many homes have gone further and tried to re-use grey water from the basins, baths and washing machines but again these are prone to failures due to the complicated and smaller scale filtration and sanitation equipment required that often require continual maintenance and tinkering. I would personally avoid any attempt at grey water reuse within a home.