Backflow Tester List

State rules

Delaware

Delaware’s Division of Public Health, Office of Drinking Water, publishes a cross-connection control guidance summary of water-system responsibilities. The summary says a public water system must designate a responsible individual who is appropriately trained and experienced in cross-connection control. The system must keep an inventory of backflow prevention assemblies and elimination methods, and it must keep records of testing, repairs, and maintenance. Those results must be retained for no less than ten years. Approved corrections and devices must conform to standards of the American Society of Sanitary Engineering, the American Water Works Association, and the American Society of Mechanical Engineers. The guidance does not create a state tester license.

Checked against official sources on October 11, 2026. Rules and links change; confirm with the office listed before you act.

Try a ZIP like 30303, “Travis County” or “Columbus, OH”
Drinking-water agency
The Delaware Division of Public Health, Office of Drinking Water, publishes the cross-connection control guidance for public water systems.
Who may test an assembly
The guidance requires a trained and experienced person designated by the public water system. It does not issue a state tester credential.
Official program page
Official page →

The guidance summary requires the public water system to prevent backflow into the distribution system. It must assess the adequacy of existing preventive measures. It must install approved backflow prevention assemblies or elimination methods at premises with an auxiliary water system and at premises deemed a high hazard. The system may use judgment when determining the need for measures at each premise. For customers whose premises are deemed a low hazard, the system may implement a public education program in lieu of assessments and installation of assemblies. That education must cover causes and dangers, how to identify cross-connections, preventive measures, and how to report a suspected cross-connection.

The same summary says acceptable water pressure, not less than 25 pounds per square inch, must be maintained throughout the public water system to reduce backflow. The system may discontinue service to a consumer because of a cross-connection or a backflow incident until the deficiency is corrected. Device standards on this page are product and correction standards of ASSE, AWWA, and ASME. The page does not say those organizations’ personnel certifications are a Delaware tester license. A property owner should ask the water system who it will accept to perform a test.

Delaware Code title 16, section 7910, says cross connections between safe and unsafe water supply distributing systems shall not be permitted unless the Division of Public Health gives written approval. It also bars plumbing or a connection that will provide a cross connection between a safe water supply and a sewage system or that will permit backflow of sewage or waste into a water supply. That statute is older public-health language. The Office of Drinking Water guidance is the practical program summary for public water systems. Neither document, in the text reviewed here, names a statewide tester roster.

Official resources in Delaware

Office of Drinking Water cross-connection guidance

Summary of public-water-system cross-connection duties, record retention, and device standards.

Delaware Code title 16, section 7910

Statute restricting cross connections between safe and unsafe supplies and connections that could backflow sewage.

16 DE Admin. Code 4462

Public drinking water systems regulation that defines backflow, containment, and a cross-connection control program.

Key facts for Delaware

What to do next

  1. Ask the water system who its trained cross-connection person will accept as a tester.
  2. Do not treat an ASSE, AWWA, or ASME product standard as a personal license; the guidance uses those names for devices and corrections.
  3. Expect the system to keep test records for at least ten years.
  4. If the premise is called a high hazard or has an auxiliary supply, ask what assembly or elimination method the system requires.

Looking for your city or county in Delaware?

We haven't found official program-level pages for Delaware we can verify yet, so we don't show local numbers here rather than guess. Here's what to use instead, in order:

  1. General Start with the statewide information above. It applies across Delaware, but cities and counties can add their own steps, fees or deadlines.
  2. Call to confirm Ask the official office. They have the current local rule, fee and form.
    Delaware Office of Drinking Water cross-connection guidance
    Website →
    Phone not shown: use the contact page on the official website above.
    Your city or county office: Local governments →
    Not sure who handles it locally? USAGov's free help line, 1-844-872-4681, or the Delaware page on USA.gov can point you to the right office.
  3. Know the current info? Tell us and include a link to the official page. We check every tip before it goes up.

Helpful guides

Backflow tester planner →

Do you serve Delaware? Get a featured listing for $30/month, clearly labeled as a paid placement.