Water Regulations for Domestic Gardens

Posted on 15th April 2014 at 4:07pm

DB valve on outside tap

Understanding Domestic Water Supply Regulations

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 supersede the old water bylaws in England and Wales.

Double Check Valves on outside taps

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. Water companies regard the water in your garden hose as high risk as it may have all sorts of contaminants in it from the ground.

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.

DB Valves for back-flow protection

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. The Water Companies regard these systems as higher risk as they will definitely have outlets next to the earth. 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. If you have multiple garden irrigation valves controlled from a single irrigation controller, you can use the 'master valve' option on most controllers to protect the DB valve from excess pressure. A DB valve works in a different way to a double check valve, so the Water Companies regard it as a 'belt and braces' approach.

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.

If you want to run pop-up garden sprinklers in the lawn, as these are underground these need an even higher level of backflow protection, with an air-gap tank installed with a pump.

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DB Valves for garden irrigation systems

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