Cross Connection Control
The Columbia Valley Water District staff is committed to providing quality, cost-efficient service in
the production, treatment, testing and delivery of safe drinking water to all residential and commercial users.
Safe and reliable drinking water is a carefully manufactured product. In order to help ensure safe
drinking water the Columbia Valley Water District has adopted a Cross Connection Control Program. This Program is a part of our effort to ensure safe and reliable drinking water and is required
under WA State Department of Health.
What is a Cross Connection?
A cross-connection is a direct or potential connection between any
part of the public water supply system and a source of contamination or pollution. The most common form of cross-connection is a garden hose, which is easily connected to the public water supply
system and can be used to apply a variety of potentially dangerous substances, including chemicals and fertilizer. Other common cross-connections include dishwashers, toilets, pressure washers,
boilers, pools, and lawn sprinkler systems.
How Does Contamination Occur
Water normally flows in one
direction, from the public water system through the customer's cold or hot water plumbing to a sink connection or other plumbing fixture. The plumbing fixture is the end of the potable water system
and the start of the waste disposal system. Under certain conditions water can flow in the reverse direction. This is known as backflow. Backflow occurs when a
backsiphonage or backpressure condition is created in a water line.
Backsiphonage may occur due to a loss of pressure in the water distribution system during a high withdrawal of water for fire protection, a water main or plumbing system break,
or a shutdown of water main or plumbing system for repair. A reduction of pressure below atmospheric pressure creates a vacuum in the piping. If a hose bibb was open and the hose was submerged in a
wading pool during these conditions, the non-potable water in the pool would be siphoned into the house’s plumbing and back into the potable water supply.
Backpressure may be created when a source of pressure, such as a pump, creates a pressure greater than that supplied form the distribution system. If a pump supplied from
a non-potable source, such as a landscape pond, were accidentally connected to the plumbing system, the non-potable water could be pumped into the potable water supply.
How to Prevent Contamination of Your Drinking Water
Protect your drinking water by taking the following precautions.
- Submerge hoses in buckets, pools, tubs, sinks, or
- Use spray attachments without a backflow prevention
- Connect waste pipes from water softeners or other treatment
systems to the sewer or submerged drain pipe.
- Use a hose to unplug blocked toilets or sewers.
- Keep the ends of hoses clear of all possible
- If not already equipped with an integral (built-in) vacuum
breaker, buy and install hose bibb type vacuum breakers on all threaded faucets around your home.
- Install an approved backflow prevention assembly on all
underground lawn irrigation systems. Remember, a plumbing permit is required for the connection of an underground lawn irrigation system to your plumbing system.