Keep Your Home Water Supply Safe

What are the odds your home water supply could be contaminated by accidental cross-connections? About 96 percent, according to joint university-government research results.

But you can easily protect your home water supply, and you don't have to be a plumber for the following quick fixits!

Municipal water is piped into your home under pressure. If the pressure drops, under certain conditions, the flow of water can reverse and travel back into the water lines. These backflow events can create serious health hazards, as documented by case studies.

Let's say you're washing the car and you toss the end of the hose into a bucket of soapy water. Or you've hooked up a fertilizer dispenser to your hose to feed the lawn.

All is well, until the pressure of the water entering your home falls. Perhaps there's a break in a main water line, or the hydrants in your area are being opened for testing or to fight a fire. Or maybe your better half has turned off the water supply while making repairs and isn't aware there's a chemical sprayer still attached to the hose.

A study by the Environmental Protection Agency (EPA) and the University of Southern California (USC) Foundation for Cross-Connection Control found that 95.7 percent of the households surveyed had direct or indirect cross-connections to a health hazard, starting with:

Hose Bibs
For 91 percent of the homes, potential cross-connections were found at exterior spigots. The good news is that backflow preventers (anti-siphon valves) are cheap, available at hardware stores, and take about 30 seconds to install.

A backflow preventer provides a physical barrier which stops water and bacteria from flowing back into the plumbing lines.

It's also wise to maintain a 2-inch air space between the end of the hose and the container being filled. There's a cute comic book for your kids that explains air gaps and cross-connections with the help of "Buster Backflow."

Toilets
The EPA-USC team noted other possible cross-connections in toilets for 61 percent of the homes evaluated.

Remove the toilet tank cover and see if there's at least a 1-inch air gap, or vertical space, between the toilet refill tube and the maximum fill level in the overflow pipe. This air gap prevents blue water flowing from your kitchen faucet from the toilet bowl cleaner in an adjacent bathroom. Here's where diagrams are helpful.

Tub and Sink Fixtures
Today's plumbing codes specify that faucets and tub spouts have a minimum 1-inch air gap over the maximum fill level of the basin or tub to prevent cross-connections. Keep this in mind when you buy new fixtures.

Other Appliances
The remaining sources of potential cross-connections found by the EPA-USC study involved heating/cooling systems and water softeners. Any showerhead on a flexible line must have a built-in backflow preventer. Otherwise, shorten the flex line so it ends 2 inches above the tub's maximum flood level. In this way, dirty water can't be sucked into the piping via a submerged showerhead.

Water-cooled air conditioners frequently lack the necessary backflow preventer on the water supply line, as illustrated.

Water softeners need a 1-1/2 inch air gap between the end of the valve drain tubing and the floor drain, laundry tub drain or standpipe drain.

Lastly, inspect your dishwasher drain line. Some states require that dishwashers have an air gap fitting on the counter top above the sink flood level. Other states permit "a high loop drain"in which the dishwasher drain line is looped upward and secured to the underside of the counter.

So it might take you 15 minutes to look for potential cross-connections in your home, and not much more time to make things right. But it's well worth your effort, wouldn't you say? Better a quick trip to the hardware store rather than gastrointestinal distress in the middle of the night!: