Backflow and what you need to know

By Don Stallsmith

At least eighty Boise residents were sickened earlier this year due to Campylobacter, nasty bacteria that found its way into the residential drinking water of these unsuspecting homeowners. The culprit was backflow issues.

Quite simply, backflow occurs when water from a business, your home, or even a neighbor’s home flows back into the water supply system. Water distribution systems are designed with the intention of the water flowing in a certain direction only. When the conditions are just right within the system, water flows in the opposite direction pushing water back into the distribution system. This is referred to as backflow and occurs when the pressure in the distribution system drops due to a water break or high fire hydrant use for a fire siphoning water, as well as any substance which may be in contact with the water from the consumer’s system into the water distribution system. This also occurs when pressure in the customer’s system becomes greater than the distribution system. This can be caused by thermal expansion from boiler/heating systems or the use of pressure pumps, etc. In doing so, the water distribution system can become contaminated.

What can you do as a homeowner? Foremost, have all changes to your plumbing system done by a licensed plumber. Furthermore, be sure that your plumbing system has the proper mechanical assemblies to prevent backflow. Most backflow preventers have been tested using stringent specifications in the laboratory and in the field. One type of backflow assembly preventer is called a hose bib vacuum breaker. A garden hose simply extends the end of your water line. Most newer hose bib faucets come with a backflow assembly already installed in the unit, but if you have an older faucet or one that does not comply with current backflow codes, you can purchase a screw-on hose bib vacuum breakers to install on all outside faucets. This ensures no harmful materials are drawn back into the hose and then into the water system. The vacuum breaker will isolate your garden hose from the rest of your plumbing system, eliminating the most likely source of residential backflow. Hoses left on the ground in a puddle or connected to a lawn/ garden chemical sprayer without the hose bib vacuum create a potential for contamination. A screw-on hose bib vacuum breaker can be purchased at a plumbing supply store for around $15. Be sure to only use listed or approved products acceptable to your water or health agency.

Other areas of backflow concern for the homeowner involve sinks, tubs, tanks, toilets, boilers, and lawn irrigation systems. All faucets need to be located so that the end of the faucet never comes into contact with the contents of the sink or tub. This prevents the contents of the sink, tub, or tank from being siphoned back into the water system. Toilets must have the correct float valve installed inside the toilet tank to ensure that the contents of the toilet tank do not get back into the drinking water system. Due to the pressure that may build up, boilers must also have an approved backflow preventer. The type of irrigation system dictates the type of backflow prevention needed. This is determined by the installation of the irrigation system and other factors, such as if water from another source such as a canal or secondary water is being utilized. Other preventative measures include surveying your home for any potential sources of water system contaminations as well as not attaching any pesticide, chemical, or any other non-potable (not safe for drinking) liquid applicator to your water line.

The City of Pocatello takes its mission of delivering water seriously, ensuring that 5.5 billion gallons of water used by annually by approximately 16,200 customers is safe and clean. In accordance with federal law, the City of Pocatello protects its water system from contamination or pollutants by conducting surveys of various facilities. These surveys determine what type of backflow protection is necessary to protect the water system and the City’s 263 miles of water pipe.  If you have any questions concerning backflow, contact me, and I’m happy to answer your questions.

Don Stallsmith is the plumbing inspector in the City of Pocatello’s Building Department. He can be reached at (208) 234-6162.