Backflow is an undesirable reversal of flow of non-potable water or other substances through a cross connection and in the piping of a public water system or consumer's potable water system.

There are two types of backflow - back pressure and backsiphonage.

A cross connection is any physical of potential connection between a potable water supply and any potential hazardous material. This connection can be created when plumbing is incorrectly installed or even by simply attaching a hose to a faucet.

Cross connections are not easy to discover, but can pose a serious threat to water quality. Federal and State regulations provide that no such connection is permissible without the installation of an approved backflow prevention assembly in accordance to the degree of hazard of the substance involved.

All homes have the potential to contain cross connections. Be aware of situations where your home water supply does or could contact non-potable liquids. If the cross connection cannot be avoided, be sure to use the proper plumbing device to prevent any liquid from backflowing into the potable water system.

For example, a hose bibb (outside faucet) vacuum breaker is a simple, inexpensive plumbing device you can attach to the faucet before attaching the hose. These devices can be purchased at most home improvement stores. Other situations require a special backflow prevention device that will isolate potable water from potential contamination.

To protect the quality of tap water in your home follow these guidelines:

1. Never allow hoses to be submerged in sinks, pools, animal feeders, chemical mixing tanks, etc.
2. Be sure your toilet flush valves have an anti-siphonage device.
3. Make sure any plumbing work done in your home is by a licensed plumber certified in cross connection control.

• Fire suppression systems
• Lawn irrigation systems
• Garden hoses - A garden hose with all the uses and attachments that you can connect to makes it a number one source for cross connection to your potable water supply.
• Any home that has retained a private well but has also been connected to the municipal system, with only a valve separating the two water sources.

Mechanical backflow preventers have internal seals and moving parts that are subject to fouling, wear, or fatigue. Also, mechanical backflow preventers and air gaps can be bypassed. Therefore, all backflow preventers have to be tested periodically to ensure they are functioning properly.

A visual check of air gaps is sufficient, but mechanical backflow preventers need to be tested by a State certified backflow specialist, with properly calibrated gauge equipment.

To obtain a list of State certified testers click on the link in the resources section of this page.