Drinking Water Hazards

Items around the house like garden hoses, kitchen sink sprayers and sprinkler systems can introduce bacteria or chemicals into the drinking water in your home.  Being aware of the hazards that can affect your drinking water will help keep your drinking water clear of potentially harmful contamination.

Potential danger from a garden hose
Garden hoses, shower heads attached to hoses and kitchen hose sprayers left in the wrong place could contaminate your drinking water when the end of a hose remains submerged in bath water, dish water or any other contaminated water.

Using a sprayer hose attachment outside to apply lawn and garden chemicals can also be hazardous.  A sudden drop in pressure inside a water line might cause these contaminants to be to be sucked back into your home's drinking water supply.  Pressure may also build up inside a hose that has been left on with a shut-off nozzle attached.  High pressure can also force poor tasting water from inside the house into your home's plumbing when a hose is left in the hot sun.

Cross connections (backflow hazards)
A cross connection is a point in a plumbing system where the drinking water supply is connected, or can be connected, to a non-drinking water source.  Potential cross connections include:  outdoor hose faucets, irrigation sprinkler systems, swimming pools, boiler systems and fire sprinkler systems.

Backflow
Two types of backflow can occur at cross connections:

1. Backsiphonage is caused by negative or reduced pressure in the water supply line.  This is not uncommon and might be the result of accidental construction damage to a pipeline or firefighters battling a nearby fire.
2. Backpressure might happen when the drinking water supply line gets connected to another system operating at a higher pressure.  Potential backflow sources include:  a booster pump, a boiler systems or other pressurized systems like high-rise building water systems.

How to Prevent Backflow

Major hardware and plumbing supply stores carry inexpensive and easy-to-install backflow prevention devices for all types of threaded faucets.  Hose faucet vacuum breakers are available for approximately $5 to $10.

Keep the ends of hoses out of contaminated water sources.

Backflow prevention assemblies for landscape irrigation systems are more expensive and, at a minimum, require a double check valve assembly.  Contact your landscape contractor, plumber, local plumbing store, or at the City of DuPont for more details.