Cross Connection And Backflow Testing

Approved Tester List

Plumbers/ Certified Contractors (See Links Below)

How can a cross connection occur?

For example, a drinking water line may enter an industrial facility and be piped to a chemical rinse tank. If a water flow reversal were to occur (due to a water line break outside, a fire next door, or similar), the chemicals in the rinse tank could be sucked into the drinking water system. This type of event is called backsiphonage. If the chemical rinse tank was pressurized at a higher pressure than the drinking water system, the chemicals could be forced into the drinking water system. This type of event is called backpressure.


Or suppose you are filing a pool with a garden hose, and the hose is submerged in the pool. If there were to be a water line break down the street causing a loss in pressure, the contents of the pool could be 'vacuumed' back into the water supply. This is another example of backsiphonage.

How do we prevent this?

Cross connections are prevented through either a physical separation or use of a backflow preventer. Physical separation means that there is a gap of air between the source of contamination and the water supply. In the swimming pool example, simply moving the hose so that it fills the pool from above the water line would prevent a backflow event.

A backflow preventer could be used to ensure that a cross connection does not occur from the chemical rinse tank example. This mechanical device, if properly installed and maintained, is designed to prevent contaminated water from entering the drinking water supply. There are many different types of backflow devices that can have different applications depending on the situation.

What are some other examples of cross connections?

Residential Examples

  • Hoses submerged in dirty buckets
  • Lawn irrigation systems
  • 50df0360c8deaa63fb76a6daba53a8f4sprinkler1Water softeners
  • Fire sprinkler systemssprinkler1
  • Water-assisted sump pumps
  • Hot tubs
  • Boilers
  • Toilet fill valves

Industrial or Commercial

  • Lawn irrigation systems
  • Fire sprinkler systems
  • Dishwashers
  • Soap dispensers
  • Hose connections
  • Food processing equipment
  • Chemical feed equipment
  • Laboratory equipment
  • Mop/slop sinks

How is this regulated?

The Michigan Department of Environmental Quality (MDEQ)requires water utilities to have a cross connection control program. This is defined in Part 14 of the Michigan Safe Drinking Water Act. Additionally, the MDEQ has published a Cross Connection Rules Manual which more fully explains Cross Connection Control Programs. The Michigan Plumbing Codealso has requirements regarding preventing cross connections

How does Grandville's Cross Connection Program work?

This program is responsible for identifying and eliminating cross connections within the City. To accomplish this, staff inspect facilities, require testing of backflow prevention devices, and educate the community through mailings and/or public outreach events.

All testable low hazard (residential) backflow deivices must be tested every 5 years by a state certified tester. All high hazard testable backflow devices must be tested annually by a state certified tester.

Who are the Certified Testers?

In order to be certified as a tester and perform work in Grandville, one must be certified by the Michigan Plumbing and Mechanical Contractors Association and approved by the City. Click on the Approved Tester List at the top of this page for a list of certified contractors.

As a homeowner, what can I do?

The most common type of homeowner cross connections are underground sprinkling systems or unprotected hoses.
All underground sprinkling systems must have a backflow device installed on them. This device is typically a pressure vacuum breaker. Homeowners are REQUIRED to have their underground sprinkling backflow devices tested every 5 years to ensure that it is working properly..

A hose bib vacuum breaker (HBVB) is a type of backflow preventer that is a cheap and easy way to prevent backflow of water through a hose. Special frost-free HBVBs are available for exterior applications.

1    2

Where can I find other information?

Please contact the Grandville Public Work's Department with any questions at (616) 538-1990 or Email