Last updated 2026-08-19
TL;DR
Delaware does not issue a state backflow tester license. Most testers keep an ASSE 5110 (or equivalent) certification and renew it on the certifier's three-year cycle. You still need the water system or county that accepts your reports to keep you on their tester list. Confirm every fee and form with that utility. No statewide processing clock exists.
Do you need a license for backflow tester in Delaware?
No. Delaware does not run a statewide backflow tester license, and the state drinking water program does not publish a tester roster or a tester application. What you need is a current third-party tester certification plus whatever paperwork the water system that owns the assembly requires.
The federal rule sits underneath that local practice. EPA's Cross-Connection Control Manual says a “certified backflow prevention assembly tester” is “a person who has proven his/her competency to test, repair, and maintain backflow prevention assemblies to the satisfaction of the administrative authority having jurisdiction” [1]. Delaware left that “administrative authority” with public water systems and, for plumbing work itself, with the Division of Professional Regulation.
If you open or repair assemblies as plumbing work, you still need a Delaware plumber license. 24 Del. C. § 1807 says no person may “engage in the practice of plumbing” unless licensed, and the statute defines plumbing to include water supply and waste systems [2]. Testing a device for a water utility report is not automatically the same thing as practicing plumbing. Repairing that device on a customer's side often is. Ask the plumbing board if your work mix includes rebuilds.
Most Delaware utilities that publish a tester list ask for ASSE 5110, ABPA, or a similar recognized tester credential. They do not ask for a Delaware tester number, because the state never created one. If a job site tells you to “get licensed in Delaware first,” they are mixing this up with plumber licensing or with another state's tester program.
How does backflow tester renewal work if Delaware has no tester license?
You renew the credential the water system actually accepts, not a state card. For most people that means the ASSE 5110 Backflow Prevention Assembly Tester certification. ASSE International certifications run on a three-year cycle, and recertification is required to keep the card valid [3].
ASSE's recertification path is either a written recert exam or, if you qualify, a documented work-experience option. The organization also requires a hands-on practical if your original path included one. Do not treat a faded wallet card as current. Utilities that still keep tester lists will drop you the moment the expiration date prints on your next test report.
If you hold an ABPA tester credential instead, you follow ABPA's recertification rules, not ASSE's. Same idea. Three-year cycle, exam or approved course, current gauge calibration. The water system cares that the card is live. It does not care which national brand you picked, as long as that brand is on its acceptance list.
Local renewal is a second, separate step. After you recertify, you send the new card, a current gauge calibration certificate, and whatever form the utility uses to stay on its approved tester list. Some systems never built a list and just reject reports from expired testers. Either way, the paper path is national cert first, then the utility file.
How much does backflow tester cost in Delaware?
There is no Delaware tester application fee because there is no Delaware tester license. Your real costs are the national recertification, the course if you need one, gauge calibration, and any plumber license you already hold.
ASSE lists recertification at $110 through an ASSE-approved recertification exam, and $160 through documented work experience. Those figures come from ASSE International's published recertification information [4]. Course tuition on top of that is not set by ASSE. Schools in the Mid-Atlantic quote their own prices. Confirm the current number with the school before you book.
A Delaware journeyman plumber license renewal is a different bill. The Division of Professional Regulation posts plumber renewal at $94 for the two-year cycle [5]. That fee does not buy you tester status. It keeps the plumbing license current if you also repair assemblies.
Gauge calibration is the cost people forget. Most water systems want a current calibration certificate on the differential-pressure gauge you use in the field. Labs set their own prices. Nobody publishes a statewide rate. Budget it every year, or on the interval your utility wrote into its spec.
First-year people sometimes buy a full kit they do not need. A $149 one-time ASSE 5110/5115 tester kit from ASSEPath covers the paper stack (application worksheets, field logs, and the forms you actually hand a utility). It is optional. You can print the same blank forms yourself.
How long does backflow tester take in Delaware?
There is no state processing clock. Delaware does not review tester files. Time is the recert class, the exam date, and however long your water system takes to update a list, if it keeps one.
ASSE recertification runs on a three-year cycle from the date on your card [3]. The written recert exam is short. The practical, if required, is scheduled by the proctor. Schools in neighboring states (Maryland, Pennsylvania, New Jersey) run tester recert classes on their own calendars. Some are one day. Some are two. Book the date that matches your expiration, not the date that looks convenient six months later.
Utility list updates are the wild card. A city water department may add you the week your email lands. A contract operator for a small community system may take a month. Nobody has good public data on that lag. The honest version is this: send the new card the week you get it, and do not schedule a test the day after an expiration if that system is picky.
If you also hold a Delaware plumber license, that renewal is on a two-year cycle set by the Division of Professional Regulation [6]. Do not mix those two calendars. The plumber card and the tester card expire on different dates.
What paper does a Delaware water system actually want?
Start with the water system's cross-connection or backflow page, not with a national myth. Many Delaware community water systems publish a tester packet or a short “approved tester” paragraph. Typical contents: a copy of your current tester certification, a photo of the gauge serial number, the latest calibration certificate, and a W-9 if they pay testers directly (most do not).
The state's drinking water rules still sit on the water system. Delaware's Regulations Governing Public Drinking Water Systems (16 DE Admin. Code 4462) require public water systems to meet federal Safe Drinking Water Act standards and to operate under state oversight [7]. Those regulations do not create a tester license. They put the duty on the system to keep the water safe, which is why the system, not Dover, decides who may file a test report.
EPA's Cross-Connection Control Manual is the document most local specs still echo. It tells the administrative authority to use certified testers and to keep records of tests [1]. When a Delaware utility writes “ASSE 5110 or equivalent,” that sentence is the local version of that EPA language.
If the system has no public packet, call the operator and ask three things: which certifications they accept, whether they keep a tester list, and where the test report form lives. Get the answer in writing. Verbal “you're fine” disappears the day a new operator starts.
What is the ASSE 5110 recertification path testers actually use?
ASSE 5110 is the Backflow Prevention Assembly Tester professional qualification standard. Recertification is every three years [3]. You either sit the recertification exam at an approved site or, if ASSE still offers the documented-experience route when you apply, you submit the work log they specify and pay the higher fee [4].
The written exam covers test procedures for the assemblies you are allowed to test: reduced-pressure principle assemblies, double check valve assemblies, pressure vacuum breakers, and the related field tests. The practical, when required, is you on a test bench with a gauge, walking the steps in order. Fail the practical and you retake it. There is no Delaware overlay on that exam.
Keep the score report and the new wallet card. Scan both the day they arrive. Water systems ask for a PDF, not a photo of a crumpled card on a truck dash. If your gauge failed calibration in the same month, fix the gauge first. A new card plus a stale calibration certificate is still a rejected report.
People coming from states that do issue tester licenses (Florida, California, and a few others) expect a Delaware form that does not exist. There is no reciprocity application because there is no Delaware tester credential to reciprocate into. Bring the national card. That is the whole file.
Does a Delaware plumber license replace tester certification?
No. A plumber license lets you do plumbing work. A tester certification is what most water systems use to decide whether they will accept your test report. You can hold one, the other, or both. Plenty of testers who only test (no rebuilds) never pull a plumber card. Plenty of plumbers who never test assemblies never sit ASSE 5110.
24 Del. C. § 1806 creates the Board of Plumbing, Heating, Ventilation, Air Conditioning and Refrigeration Examiners and gives it the power to license plumbers [8]. The board's rules live in 24 DE Admin. Code 1800. Those rules talk about apprentices, journeymen, masters, and continuing education for plumbers. They do not talk about backflow tester cards [9].
If you rebuild an assembly on the customer side of the meter, you are in plumber territory. If you only perform the field test and hang a tag, many systems treat that as tester work under their cross-connection program. The line is local. When it is fuzzy, ask the plumbing board and the water operator the same question and keep both emails.
Continuing education for the plumber license does not automatically recertify ASSE 5110. Do not count a Saturday plumber CE class as your tester recert unless the provider is an ASSE-approved recertification proctor and you sat the actual recert exam.
What about New Castle, Kent, and Sussex County differences?
Counties do not issue tester licenses either. The split you will feel is between large municipal systems and small community systems, not between the three counties as legal jurisdictions.
City of Wilmington, Artesian, Tidewater, and similar larger systems are the ones most likely to keep a tester list and a standard report form. Smaller systems may accept any current ASSE or ABPA card and file the report in a folder. Fire districts and private well systems are a third pile. A private well serving one house is usually outside the public-water tester list entirely.
New Castle County's plumbing permitting is separate from tester certification. If a job needs a plumbing permit for a rebuild or a replacement, that permit runs through the county or city building department, not through a state tester desk (there is no such desk). Do not send a tester recert packet to a building department and expect a license back.
If you work across the state line into Maryland or Pennsylvania, those states have their own water-system rules and, in some counties, their own tester lists. Delaware paper does not travel. Take the national card and start the other state's local file from zero. Readers comparing state paper often look at backflow tester renewal in Maryland next, then the Pennsylvania path if they cover that border.
What first-year testers in Delaware waste money on
A second gauge before the first one is calibrated. Fancy report software when the utility still wants a one-page PDF. A “Delaware backflow tester license course” sold by a school that is really just ASSE 5110 with extra slides. If the school cannot show you the ASSE approval number, walk.
You do not need a Delaware business license solely because you test assemblies, but you may need one if you operate as a contractor. The Division of Revenue handles business licenses. That is a tax credential, not a tester credential. Confirm with Revenue if you are unsure. Do not mail that form to the drinking water program.
Insurance is a judgment call. Some water systems ask for a certificate of insurance before they will put you on a list. Some never ask. Get the minimum the system wrote down. Extra policies sold as “required for all Delaware testers” are usually a sales pitch.
Study time is real. The recert exam is not a formality if you have not tested a PVB in two years. A weekend with the ASSE procedures and a bench is cheaper than a failed practical and a second trip.
How Delaware testers should track dates so a card does not lapse
Put three dates on one calendar: ASSE (or ABPA) expiration, gauge calibration due date, and plumber license expiration if you have one. They will not line up. That is normal.
ASSE sends renewal reminders if your contact info is current. Do not rely on the reminder. Cards lapse because people move shops and the email dies. Ninety days out, book the recert exam. Thirty days out, scan the new card to every utility that has you on a list.
If a card lapses, you are not a current tester. Reports you file after the printed date are the water system's problem and then yours. Some systems will accept a late recert with a letter. Some will not. There is no Delaware grace period because there is no Delaware card.
Keep a folder with the current card, the last two calibration certificates, and a blank copy of each utility's report form. That folder is the whole practice. Everything else is noise.
Where Delaware testers get tripped up on reports and tags
Wrong serial number. Gauge out of calibration. Test date after the tester card expired. Assembly address that does not match the water account. Those four errors cause more rejected reports than any exam question.
The water system owns the official record. Your copy is a field copy. If their form has a “tester certification number” box and you only have an ASSE number, put the ASSE number and the expiration date. Do not invent a Delaware number to look official.
Tags on the assembly should match the report. If you hang a tag that says the RP passed and the report says it failed, you created a record the system cannot use. Fix it in the field the same day.
Repair reports are a separate sheet from test reports on most forms. If you rebuilt the assembly, say so, and if you needed a plumber license for that rebuild, your plumber number belongs on the repair line, not as a fake tester license.
How this compares to states that actually license testers
Florida, California, and a handful of other states issue or recognize a tester credential at the state or county level and put a renewal fee on that credential. Delaware does not. That is the whole comparison.
The upside is less paper with Dover. The downside is you cannot call one state office and ask “am I legal to test anywhere in Delaware?” The answer is always “ask the water system.” People who like a single statewide roster will hate this. People who already hold ASSE 5110 will find Delaware easier than a state that makes them sit a second exam.
If you maintain credentials in more than one state, keep a simple matrix: state or system name, what they accept, expiration, and the person who last confirmed it. Update the matrix when a card renews. For the Alabama-style state path see backflow tester renewal in Alabama. For a western contrast, backflow tester renewal in Arizona and backflow tester renewal in Colorado show how different the paper gets once a state or county actually issues a tester card.
Frequently asked questions
Do you need a license for backflow tester in Delaware?
No state tester license exists. Delaware does not issue or renew a backflow tester credential. You need a current national tester certification (usually ASSE 5110 or equivalent) and whatever file the water system that receives your reports requires. Plumbing work on assemblies still needs a Delaware plumber license under 24 Del. C. § 1807.
How much does backflow tester cost in Delaware?
There is no state tester fee. ASSE publishes recertification at $110 for the exam route and $160 for documented work experience. A Delaware journeyman plumber renewal is posted at $94 for two years if you also hold that license. Course tuition and gauge calibration are extra and set by the school or lab, not by the state.
How long does backflow tester take in Delaware?
There is no state processing time. Recertification follows the three-year ASSE (or ABPA) cycle. The class and exam are scheduled by the school, often one or two days. Utility list updates, if the system keeps a list, vary and are not published. Confirm the current wait with that utility. No approval timeline is guaranteed.
Who regulates backflow testers in Delaware?
No single tester board exists. Public water systems set tester acceptance under their cross-connection programs, with state oversight of public drinking water through 16 DE Admin. Code 4462. The Division of Professional Regulation licenses plumbers. EPA's Cross-Connection Control Manual is the federal guidance those local programs still cite.
Is ASSE 5110 required to test in Delaware?
Most water systems that publish a standard ask for ASSE 5110 or an equivalent such as ABPA. It is not a statute. It is the credential the administrative authority decided to accept. Confirm the current list with the system that will receive your report before you book a recert class.
How often do you renew a backflow tester certification?
ASSE certifications are valid for three years. Recertification is required to keep the card valid. ABPA uses its own recert cycle. Delaware does not add a fourth date. Put the printed expiration on your calendar and recertify before that day, not after.
Does a Delaware plumber license let me test backflow assemblies?
Not by itself. The plumber license covers the practice of plumbing. Water systems still want a current tester certification before they accept a test report. If you rebuild assemblies you likely need both. Ask the plumbing board and the water operator when the job includes repairs.
Can I use an out-of-state tester license in Delaware?
Delaware has nothing to transfer into. Bring the national card the local water system already accepts. A Florida or California tester license does not become a Delaware tester license, because that license does not exist. Start a file with each Delaware system you will report to.
What happens if my tester card expires mid-season?
You are not a current tester after the printed date. Reports filed on an expired card are at the water system's discretion and often get rejected. There is no Delaware grace period. Recertify early. Send the new card to every system that lists you as soon as you have it.
Do I need a business license to test backflow in Delaware?
Testing itself is not a state occupational license. Operating as a contractor may require a Division of Revenue business license. That is a tax credential. Confirm with Revenue for your structure. Do not send that application to the drinking water program or to the plumbing board and expect a tester number back.
Where do I send renewal paperwork in Delaware?
To the certifying body (ASSE, ABPA, or whichever issued your card) and then to each water system that keeps a tester file. There is no Dover tester desk. If someone gives you a state tester PO box, they have the wrong program. Confirm the utility email or portal before you mail originals.
Is gauge calibration part of Delaware renewal?
The state does not set a calibration rule for testers. Water systems almost always want a current calibration certificate on the field gauge. Treat calibration as part of staying reportable, even though it is not a Delaware statute. Use the interval the utility wrote, not a guess.
Sources
- U.S. EPA Cross-Connection Control Manual (EPA 816-R-03-002): Defines a certified backflow prevention assembly tester as a person who has proven competency to the satisfaction of the administrative authority having jurisdiction.
- Delaware Code Title 24 § 1807 License required: No person may engage in the practice of plumbing in Delaware unless licensed under the chapter.
- Delaware Division of Professional Regulation, Board of Plumbing/HVACR: Delaware posts the journeyman plumber license renewal fee at $94 through the Division of Professional Regulation.
- Delaware Division of Professional Regulation, Board of Plumbing/HVACR: The Division of Professional Regulation is the board that licenses Delaware plumbers and publishes renewal information.
- 16 DE Admin. Code 4462 Regulations Governing Public Drinking Water Systems: Delaware's public drinking water regulations govern public water systems and do not create a backflow tester license.
- Delaware Code Title 24 § 1806 Board of Plumbing, HVACR Examiners: Statute creates the Board of Plumbing, Heating, Ventilation, Air Conditioning and Refrigeration Examiners with authority over plumber licensing.
- 24 DE Admin. Code 1800 Board of Plumbing, HVACR Examiners: Board rules address plumber licensure and continuing education and do not establish a backflow tester credential.
- Delaware DNREC: DNREC is the state environmental agency; it does not publish a statewide backflow tester license application.
- Safe Drinking Water Act, 42 U.S.C. § 300f et seq.: Federal Safe Drinking Water Act is the statute under which states regulate public water systems, including Delaware's primacy program.