How to gain from rain with rainwater harvesting (or what is in it for me?)

More of us are realising that our water is precious. The UK has been spoilt so far: we have had cheap and plentiful water, but this is changing. We need to use water more efficiently. But however “green” we are, we all want to know how much it will cost us and save us.

Costs obviously vary depending on individual needs and whether the collected rainwater is to be used just for outdoor use (irrigation, outdoor-cleaning) or inside the house as well for supplying WCs and washing machines. For rainwater use in the house, separate rainwater supply pipes to the appliances are needed making installation more cost efficient in the context of a new build or a renovation project. And if the tank is to be underground, then the hole has to be made. However, this need not be expensive in comparison to the overall cost of the building or renovation project.

The gains. The investment will be worth it. In August 2008, ten water companies applied for price increases that could lead to a 40% rise in water bills within 5 years. Using rainwater in combination with a metered mains water supply makes it more and more realistic to save on water bills. In addition, investment in a rainwater harvesting system could increase the value of a new or renovated home by many times the cost of the initial equipment. Purchasers view sustainable options such as rainwater harvesting as an attractive and necessary addition to the contemporary home. And the larger the tank installed, the more chance of continuing irrigation during mains water shortages.

And at long last the official pressure is on to use rainwater:

• The Code for Sustainable Homes which became mandatory in May 2008, assesses homes for reduction in drinking water consumption and flood risk. All social housing must be built to Code level 3, reducing daily consumption from 160 to 103 litres a day. Private housing does not have to meet this level but a rating is compulsory and must be included in the Home Information Pack. A nil rating will not attractive to potential purchasers.

• Planning applications with rainwater harvesting are favoured.

• Planning regulations changed in September 2008 to encourage use of permeable surfaces and rainwater harvesting to offset flood threats from hard standings round houses.

• All new homes must have meters and water boards must install meters free of charge to existing households. Records show that metered homes use 10% less water; having a meter and using rainwater could reduce your water bill.

• Businesses can benefit from the Enhanced Capital Allowance scheme to offset the installation cost of rainwater harvesting against tax.

• Businesses have a tax incentive (see above) and in the future the Government should implement grants such as exist in Germany where in some areas a grant of £1000 is given towards the cost of installation. Germany now has 50 000 rainwater harvesting systems installed every year (500 000 in total).
  
  
  A 2003/04 survey of English Housing found that 18,908,000 households have a garden, patio, yard, roof terrace or large balcony: just think how much water we could save if everyone used rainwater!