Most people are unaware that there are legal requirements to take into consideration when connecting an irrigation system to a domestic garden tap. This simple guide provides you with the information you need to make sure you stay on the right side of the law!
What you can connect to the mains water supply is regulated by an Act of Parliament – the Water Supply (Water Fittings) Regulations 1999; these regulations superseded the old water bylaws in England and Wales.
If you are a domestic house then you must have a double check valve on all ‘hose union’ taps – outside taps to you and I. The double check valve is designed to prevent water and contamination flowing backwards from the garden and into the water main.
With a double check valve fitted, then you can run border sprinkler systems which have their sprinklers more than 150mm above ground level. You can also use a hand-held hose.
If you want to run a drip system (either for borders or hanging baskets) then you also need a DB Valve. This is a special valve which fits onto the tap or after a timer which again prevents back-flow. You still need the double check valve as well, but the DB Valve provides a ‘belt and braces’ solution. The DB Valve has to be fitted higher than the highest dripper and has to be fitted after the tap or timer, as it will not stand full mains pressure for prolonged periods of time.
One of the sad things about many of the ‘consumer’ irrigation companies is they never tell the customer that a DB Valve is necessary to comply with the law.