What is a Cross-connection?
A cross-connection is a point in a plumbing system where contaminants can be introduced into the potable drinking water supply. Examples of cross-connections include a herbicides-filled sprayer hooked to your garden hose being used to apply insecticides to a lawn, or a piped connection providing potable feed water to an industrial process. Without a backflow preventer valve in place, contaminated water can backflow into the piping system and contaminate your drinking water. This especially happens If the water pressure in your house drops, drawing water from garden hoses, wash basins, boilers, lawn sprinklers, swimming pools, etc., into your home's water supply. Backflows due to cross-connections can pose serious health-hazards and therefore, it helps to know about possible cross-connections at home, and nip them in the bud before they lead to backflow.
How to Prevent Cross-connections at Home?
If you use a garden hose to fill buckets, tubs or pools, try not to immerse the hose in water, and leave some air gap between the level of liquid and whatever container you are filling. Secondly, Install a vacuum breaker valve on each outside spigot. Failure to take both of these measures may result in Contaminants getting sucked from these systems back into your main water supply. Without a backflow preventer in place, chlorinated water from pools or even water containing fertilizers from lawn sprinkler systems will end up in your water supply. If you are using a sprinkler system, connected to a hose, to spray the lawn with chemicals or fertilizer, be sure to install a backflow device at some height above the ground and above all sprinkler heads in your yard.
Bath Tub Faucets
If you still use an old bathtub with a faucet located inside the tub, you may have a cross-connection at home. As you fill the bathtub, the faucet becomes submerged into the bathtub, and in case of a backflow, soapy water can be drawn into the main water supply. The best way to remedy this situation is to replace the faucet with one that is located well above the spill line of the fixture. If changing the faucet is not an option, another remedy is to install a vacuum breaker on the water supply pipes. The back flow device will prevent contaminated water from flowing back into the potable water supply. Also, make sure to get all the check valves professionally assessed once a year for possible backflow.
If you have a water heater at home, Pressure may build up inside the boiler. If at any point, the water pressure in the boiler exceeds the pressure in the main supply line that is used to feed the boiler, back-pressure may cause the water to flow back in to the potable water supply. This water may contain anti-corrosion chemicals that are added to the boilers and may lead to serious health hazards if consumed. Installing a backflow preventer is the only protection against back-pressure and back-siphonage.
Toilet tanks contain water that is needed to flush the waste material to the sewer system. The water that is used for flushing enters the tank at the bottom through a small hose. This water usually sits stagnant, and may be home to bacteria and algae. If the anti-siphon ballcock inside the tank isn’t functioning properly, the stagnant water inside the flush tank can end up flowing back into the drinking water in your home. In addition to choosing the correct type of float valve, also make sure that it is installed above the water level in the tank. Also, it helps if the bowl refill tube is above the water line.
Other Cross-connection sites at home
If the drain hose of the dishwasher is installed without any air gap, there’s a potential cross-connection at the dishwasher. However, you can forgo the air gap if the drain line is fastened as high as possible under the countertop. Similarly, to prevent cross-connection with your washing machine, try to install a single lever shutoff valve that closes off the water supplies to prevent flooding if one of the hoses breaks. As for the faucets at your sinks, make sure that each faucet is at least an inch above the top edge of the sink or tub to avoid any cross-connections.