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1. What is a cross connection?

A cross connection is an actual or possible pathway between our drinking water supply and a source of contamination or pollution.

2. Why do such cross connections exist?

Plumbing is sometimes installed by persons who are unaware of the dangers of cross connection. These connections are sometimes made as a simple matter of convenience, with unintended consequences. And then, sometimes they are made with reliance on inadequate protection.

3. What is a Cross Connection Control Program?

A Cross Connection Control Program is an organized and structured program to identify and eliminate unprotected cross connections in order to prevent backflow. It is a cooperative effort between the City of Durango’s Water Treatment Plant, health officials, property owners, and certified testers to ensure that our water is protected both in the city main and within buildings.
Inquiries about the Cross Connection Control Program:
Ph: (970) 375-4882
Email
or direct mail to
105 Sawyer Dr.
Durango, CO 81301

4. What is backflow?

Backflow is the undesirable reversal of flow of a liquid, gas, or other substance in a potable water system as a result of a cross connection. To prevent backflow from occurring, a backflow preventer—either an assembly or device must be installed.

5. What is a backflow preventer?

An approved assembly, device, or method that prohibits the backflow of water in water systems. The backflow assembly or device may be installed at the water connection between the city main and a building, or it may be installed at the source of possible contamination or pollution.

6. Why would backflow need to be prevented?

Backflow can be hazardous. In the EPA’s “Best Practices Guide”, it is stated: “Cross connections are ever present dangers that exist in most water systems and can result in serious chemical or microbiological contamination events in drinking water systems.” Backflow can occur from something as simple as a garden hose left in a bucket of cleaning solution, but can also be much more serious.

One example of what can happen occurred within 55 miles of Durango at a public school. A chemical used in the heating system boilers backflowed into the drinking water. Samples taken determined that the chemical was chromium in levels as high as 700 parts per million. The head chemist said that it was miraculous that no one was seriously injured or killed. They were lucky. The yellowish water was discovered by a home economics teacher before school started and proper precautions were taken.

7. How will a backflow preventer affect my plumbing system?

A backflow preventer may create a slight decrease in pressure, however,
in our area, the water pressure is typically high and actually requires a
pressure reducing valve. So, a slight decrease in pressure should not be
a problem.

If you have a water heater tank, the installation of a thermal expansion tank
will be required. With a backflow preventer installed on the water line
coming into your building, expanded water from a water heater cannot return
to the potable water supply. It is now a “closed” system. The water in your
tank, as it expands from heat, will have nowhere to go. The solution is a
thermal expansion tank. More on this subject is available in a pamphlet
entitled “Protect Your Water Heater from Thermal Expansion” available from
the Cross Connection Control Program.

8. Why do backflow assemblies need to be tested periodically?

Backflow prevention assemblies have internal seals, springs and moving parts that are subject to wear, fatigue and fouling. Routine testing helps ensure that the mechanical device is in proper working order.

9. Will my water service be interrupted for backflow prevention assembly testing?

Yes, standard testing procedures require that the water service be turned off for testing. Depending on the type of assembly, the time needed is from 10 to 30 minutes. Additional time may be needed if repairs are required.

10. How much will it cost to have my backflow prevention assembly installed and tested?

Costs will vary depending on size, location and type of assembly and
whether or not the assembly will be tested during normal working hours.
You are encouraged to obtain multiple quotes for comparison.

Installation may be performed by a licensed plumber, but testing must be
done by a licensed, certified tester. The Cross Connection Control Program is
able to provide a list of all licensed, certified testers.