subject: The Ten Main Tips For Rainwater Harvesting [print this page] Surprising as it may seem, England is short of water, and there is now official encouragement to reduce mains water consumption both by maximising the use of rainwater and using water-efficient appliances. You may have seen recent ads by DEFRA in national newspapers exhorting us to save water. As yet there are no grants or tax incentives for the homeowner to install rainwater harvesting systems. However, building regs are changing in 2010 to make a 120 litre maximum per person per day the norm and planners now often require rainwater harvesting.
Here are 10 key points to be considered when installing a system.
1. Bury the tank underground: the 10 degrees Celsius cool of the ground inhibits bacterial action and the water does not go yellow.
2. Your rainwater system should be planned early: with the architect, you must check the inverts, which are the levels of the tank and drain/soakaway and rain pipes. Also the tank should be buried when the first part of the groundworks are being dug.
3. Choose a supplier which provides an accurate tank size calculation and a written quote conform with BS8515 2009: you want to be certain to have the trouble-free equipment which will get the approval of your council inspector.
4. If you are not on the main drain, dig a double size soakaway for tank overflow and debris: the filter in the head of the tank is self-cleaning. Water flowing over it sends debris out through siphon to drain or soakaway. No maintenance.
5. Equip the submersible pump with a floating intake. Why? Because it skims the freshest and cleanest water from just below the surface of the water.
6. Equip the submersible pump with a float switch: even if the pump has dry run protection, there is a risk that it would burn itself out when the tank empties repeatedly in summer. Your mains top up (if it's the sort that admits mains water into the rain tank) should also prevent dry running but the flow might be slower than the pump can shift.
7. If you have ground water within a metre of the surface, concrete the tank in: otherwise when it's empty its buoyancy will float the whole tank out of the ground.
8. Ensure that all the downpipes off the house are connected to the tank: get all the possible water off the roof when it rains.
9. Do not run surface water into the rainwater tank: you'll want to avoid oil spills and dog mess getting into the water if you're flushing toilets and washing clothes with it.
10. A smart header tank with your rain system should be considered: it reduces electricity use by ten, reduces wear and tear on the pump and appliances (gentle gravity feed) and ensures water supply in a power cut. However, do not fit a standard header tank as, in the heat of the roof space, the rainwater will turn yellow through bacterial action when you go away on holiday.
That's it in a nutshell. It's not terribly difficult to fit a rainwater harvesting system. For an average investment of #2000 to #3000, to make a sustainable difference this is the simplest and least expensive of the many green options you can take.
