Rainwater Harvesting Guide

Rainwater harvesting is the collection of, and storage of rainwater that would otherwise flow down gutters into the drain or a septic tank. Rainwater is stored in tanks ranging from 200 litres 20,000 litres, with the most popular for detached family houses at 6,500 litres. The rainwater is not considered potable by the UK Building Regulations but state-of-the-art filtering provides clear water which is used for drinking in many parts of the world.

Your tank kit typically comes with filter, pump and other standard equipment to keep collected water clean. The larger the tank you have, the more money you will eventually save and the more protection you will give your garden during droughts and possible hosepipe bans.



You can save on your water bill if you have a meter. Government reports estimate that 70% of customers see their bills reduced with a meter by 10 to 15% because of the user's awareness that mains water costs money. All water boards have to install a meter at the request of the householder. Installation is free, and some boards provide the meter as well

Typically half your water bill is for mains water supply and half is for drainage. Most calculation of rainwater use for flushing toilets and washing clothes shows that water consumption can be halved. This would therefore knock about 25% off your water bill. In august 2008, 10 water boards applied for price increases that could lead to a 40% rise within 5 years; savings will become more significant.


Rainwater can be used for all outdoor uses: watering the garden, washing cars, cleaning patios, drives and windows, topping up swimming pools, ornamental ponds and hot tubs. With some plumbing alterations, it can also be used inside the house to flush WCs and feed clothes washing machines

Besides saving on drinking water use, rainwater use encourages less build-up of calcium deposits in appliances. The diversion of rainwater to the storage tank can in many situations attenuate flooding.

Each person in the UK uses about 160 litres of drinking quality water a day. Nearly half of this amount need not be drinking water. It seems crazy to bring in drinking water from miles away via your water board to water your garden or clean your car when you could provide water directly from your own roof. It is now recognised that the south east of England in particular is short of water (London has less water available per capita than Madrid or Istanbul). April 2007 was the driest on record, but then June 2007 was the wettest on record.

Southern Counties
Heating & Plumbing

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