Bradford City Water Authority

28 Kennedy Street, Bradford, Pennsylvania 16701

Backflow & Thermal Expansion
How They Affect Your Plumbing System

The Danger of Backflow

Safe drinking water is so commonly available in this nation that we normally assume any water from a faucet is safe to drink.  The Bradford City Water Authority (BCWA) works hard to insure that the water we deliver to our customers meets or exceeds all health standards.  However, a potential threat to your drinking water exists.  The threat is backflow, or cross-connection, and it can turn a pure glass of drinking water into a lethal brew. 

Here's How It Works...

Say you are watering your garden with a fertilizer or pesticide applicator attached to your hose.  The phone rings, and you leave the garden.  While you are chatting, there is a

pressure fluctuation in our system that causes a vacuum.  Like a straw, the vacuum will pull your pesticide-laced water into the public water supply.  The next time you or your neighbors turn on a faucet, the water could be laced with the pesticides.
Backflow is not just a theoretical possibility.  There are many documented cases of this happening.

Eliminating The Threat...

You can substantially reduce this threat to drinking water by installing a backflow preventer, which allows water to pass through it in only one direction.  The Safe Drinking Water Act

requires the installation of these devices.  The BCWA also requires these devices on water lines serving our industrial and commercial users.  These customers pose the greatest backflow risk to the water supply.  Although the risk from residential customers is not as large, all customers must have backflow preventers installed to make this layer of protection successful.  It only takes one home without one of these devices to contaminate the water supply.

Thermal Expansion

Once we install a backflow preventer in your home, water will be unable to flow back into the public water pipes.  The backflow preventer creates an isolated or closed  plumbing system.  For some homeowners, this could produce leaky faucets or set off the relief valve on hot water heaters.

Why Does This Happen?

The culprit is Thermal Expansion.  Before the backflow protection device was in place, your hot water heater warmed the water causing it to expand.  As the water warmed, ther

mal expansion pushed it back into the public water supply, another example of backflow.  Once the backflow preventer is installed, the water can no longer expand in this direction and a plumbing system that is not up to current code could experience the conditions mentioned above.  If your plumbing system is faulty, it could fail once the system is closed.  For example, if thermal expansion exerted itself and the hot water heater relief valve was stuck, the hot water heater could develop a leak.

Who is Affected?

Most customers will never experience these problems.  For the majority of those that do, simply lowering the temperature setting of the hot water tank to 115-125 degrees (which is sufficient for most purposes) will eliminate the problem.  However, we strongly encourage you to make sure your plumbing systems are up to current building code standards.  You should consult a certified plumber if you have any doubts about your plumbing's condition.  A plumber may recommend the installation of a thermal expansion tank if you have a hot water heater or a pressure reducing valve if your water pressure exceeds 75 pounds per square inch (psi).  The illustration above shows these devices installed in a typical basement.  As an added note, these devices will pay for themselves by protecting your plumbing system and conserving water by helping to prevent failures of your plumbing fixtures.

The BCWA, through our backflow protection and other initiatives, strives to produce water of the highest quality and safety at a reasonable cost.  With the installation of a backflow preventer, you can rest assured that you are helping to protect your health and welfare as well as that of your neighbors and the community at large.

Home Page