Backflow Prevention Explained

A backflow prevention devicePreventing Contamination

The Alameda County Water District works hard to protect your drinking water from contamination. This effort begins at the well or watershed where your water is collected, and continues through the entire treatment and distribution process. But what about after the water reaches your home or business? Who protects the water from the meter to your glass. Read on for some important information about the hazards of backflow, and what we all can do to maintain the safety of our water supply.

ACWD's Cross Connection Control Program

Fortunately, there have not been any documented backflow incidents impacting our local water system, and we are taking steps to keep it that way. ACWD's Cross Connection Control Program, which fully satisfies the requirements of Title 17, begins with the identification of businesses, industries, and residential areas that are likely to contain cross connections. As mandated by the state, an on-site survey of the property is conducted by one of our certified Cross Connection Specialists. They often suggest ways to protect the internal water system against backflow and, if necessary, ask the consumer to install a backflow prevention device at the meter that will protect the public water supply. After the device is installed, the law requires that it be tested by a certified test person at least once a year.

Backflow Hazards at Home

How many times have you put a garden hose in a bucket of soapy water to wash the car? Or sprayed insecticide with a garden hose sprayer? Or attached a hand spray attachment to the kitchen faucet to wash your hair or the dog? These seemingly harmless actions create cross connections that could endanger the health and safety of you, your family, and your neighbors.

The danger comes when the hose comes in contact with a harmful substance. If the pressure in the water main drops while the hose is submerged in contaminated water, then the water (and whatever is in it) could be sucked back into your pipes and the drinking water supply. Water pressure drops are not uncommon. They can occur when hydrants are opened to fight fires or during repairs to a broken water main. Fortunately, keeping your water safe from these contaminants is easy, as illustrated in this diagram (PDF).

Private Wells

Backflow can also occur in the absence of a water main pressure drop. For example, some homes have backup water systems supplied by private wells or springs. If these systems are connected and overcome the pressure in the public water supply, backflow will occur. Because these private supplies are not tested and regulated by governmental agencies, they may pose a hazard to the potable water system and must be equipped with proper backflow prevention devices.

Commercial-Industrial Requirements

In commercial or industrial situations, water often comes in contact with different types of hazardous substances, whether it be for mixing, diluting, flushing, or cleaning. State law requires that certain businesses be surveyed for potential cross connections and that proper backflow prevention devices be installed to protect the public water supply. ACWD surveys manufacturing plants, hospitals, mortuaries, dental offices, dialysis centers, veterinary clinics, doctors' offices and many other businesses in order to identify potential hazards to the water system.

If your business requires a survey, we will contact you for an appointment and meet with you at your facility to identify specific hazards and discuss the applicable backflow prevention requirements.

We realize that there is some inconvenience and often some expense in complying with these requirements. Our Cross Connection Specialists will make every effort to work with you to facilitate the installation and testing of the appropriate device if needed.