To safeguard public health by protecting your water supply from possible contamination, the District requires installation of backflow prevention devices where plumbing systems are exposed to potential contamination or poorer quality water.

In the event of a malfunction in consumer pressure equipment and/or a sudden drop in pressure in the District system, these devices prevent water which has already left the District system from being siphoned back in, guarding the system from possible pollution.

Some examples of where protective devices (such as reverse pressure principle check valve assemblies) are required are: residences with an additional water supply (such as a well or the canal), swimming pools or irrigation systems supplied by a separate water service or without a satisfactory air gap or anti-siphon device on the inlet line, buildings with internal booster pumps systems, buildings more than three stories high, premises where there are hazardous materials under pressure or where toxic materials are used (hospitals, mortuaries etc.) and sewage pumping or treatment plants.

The backflow prevention devices are supplied and installed by the District at customer's expense. District inspectors check these devices periodically to make sure they are operating properly, and repair or replace any failed or improperly functioning devices. Annual inspection and service is required by certified backflow prevention device testers and results shall be sent to the District.

While GWD has an inspection program to identify situations requiring backflow prevention devices, conditions can change (you might have dug a well on your property, for example) and we need to be made aware -- for your own safety and the safety of others. If such a situation exists on your property, or you'd like more information about the regulations concerning the District's backflow prevention program, please call the District's Crossconnection Prevention Program Administrator, at 964-6761.

• If you have a dual water supply, don't interconnect the systems. Make sure that all plumbing meets code requirements.
• If your home has a swimming pool, there should be no faucets within 50 feet of the pool, unless the faucets are equipped with anti-siphon devices (Uniform Plumbing Code).
• Make sure your home's irrigation system (sprinklers, etc.) is equipped with anti-siphon valves.
• If you have a hobby or activity that requires running water (such as a home darkroom for photography), make sure there is an air gap (a space) between the hose and the water in your sink.

Many water, natural gas, electric and telephone lines lie harmlessly underground -- until someone carelessly digs into them. To prevent possible injury, interruptions of service or the loss of valuable water or energy, call Underground Service Alert toll free (USA) at 1-800-642-2444 two working days before you begin any excavation -- planting trees, landscaping , trenching, post holes, etc. Describe where you plan to dig and then GWD and other USA sponsors will tell you whether or not there are any facilities in the area and, if so, approximately where they are located. If needed, a representative will visit the location and mark them for you.