Cross Potable and Contaminated Water Connections

A cross-connection is present when there is a possibility that the potable drinking water could mix with the non-potable wastewater. The most logical occurrence is when the pressure in the supply system changes or is turned off, and non-potable water is drawn into the supply system. Examples:

• When the faucet outlet or spout is below the rim or upper-most level of a sink or tub.A spout may be very close to the rim, and if someone adds or raises the level of the rim with some typ of tile on the counter top, you would have a cross-connection.

• A sink or bathtub with a sprayer or shower head with a hose that is below the rim could allow contaminated water to be drawn into the supply piping if the pressure goes off or is turned off.
• The toilet supply may become detached and fall below the water level or drain overflow tube.
• The water in the tank may be drawn into the supply line if the pressure goes off.
• A garden hose could end up in a number of undesirable areas that could draw contaminated materials into the hose or supply system.
• Contaminated water could drain into a dishwasher if the sink drain backs up. This may not affect  the clean dishes, however, it is a dangerous condition that could have significant ramifications.

Conditions have to be just right for these problems to occur, but they are possible. Stagnant, contaminated fixtures can impact the good water coming through a compromised fixture for months or longer if the conditions allow the contaminants to flourish, such as in the bottom of a dishwasher.