Got a backflow test letter? What it is and what to do

What backflow is

A cross-connection is an actual or potential link between drinking water and non-drinking water plumbing. These links can occur where the public system feeds irrigation systems, fire sprinkler systems, and other piping. Backflow is the unintended reversal of flow through a cross-connection. One cause is pressure in the public system dropping below pressure in the connected plumbing. EPA calls the result a potentially serious public health hazard.

SourceEPA Distribution System Toolbox: Cross-Connection Control · accessed Oct 10, 2026

EPA’s manual adds that there are numerous well-documented cases where cross-connections contaminated drinking water and spread disease. It says all municipalities with public water supply systems should have cross-connection control programs.

SourceEPA Cross-Connection Control Manual · accessed Oct 10, 2026

Why the letter came to you

A backflow preventer is a device in the water line that stops contaminated water from flowing back into the clean supply. Birmingham Water Works explains that it’s mechanical, with seals and springs that can fail from wear, fouling, or fatigue. That’s why it’s tested: Birmingham requires every residential and commercial property with a backflow preventer to test it every year, and new installations within 30 days.

SourceBirmingham Water Works Board: Backflow Testing FAQ · accessed Oct 10, 2026

Rules vary. EPA notes that cross-connection programs differ by state and municipality.

Who tests it, and who pays

In Birmingham, the homeowner is responsible. The letter comes with a current list of approved testers and a blank test and maintenance form. You hire a certified tester from that list, and the tester sends the completed form to the utility.

The tester sets the price. Birmingham says prices vary depending on who you call and recommends getting multiple quotes from the approved list. You also can’t remove a required assembly without the utility’s approval.

SourceBirmingham Water Works Board: Backflow Testing FAQ · accessed Oct 10, 2026

Deadlines and what happens if you skip it

Birmingham’s windows show how fast this can move:

• Annual notice: testing must be done within 30 days of the date on the letter.
• Final notice: 10 days from its date to tell Cross-Connection Control the test is done. After that, the utility has the authority to terminate service.
• Failed test: 30 days to repair or replace the device. If it’s still out of compliance, all water service to the property is discontinued until it complies.

SourceBirmingham Water Works Board: Backflow Testing FAQ · accessed Oct 10, 2026

Your own utility’s letter sets your real deadline. Use the date counter at the top of this page with its numbers.

Check the letter is from your utility

If you’re unsure, look up your utility’s phone number on its own website or your bill, not the letter, and ask for the cross-connection or backflow department. Confirm the deadline and the tester list there.

For more detail, EPA points to state drinking water programs, building code or plumbing authorities, and health departments.

SourceEPA Distribution System Toolbox: Cross-Connection Control · accessed Oct 10, 2026

Keep it separate from your water bill

The test is a service you buy from a tester, not a usage charge. If irrigation is also pushing your bill up, that’s a separate question. Check the timer and the bill’s usage history.