Median Pay by Area
- Philadelphia-Camden-Wilmington (PA-NJ-DE-MD)
- $66,680 a year
- Dover
- $62,410 a year
- Sussex County (nonmetropolitan)
- $60,320 a year
Delaware wastewater operators
The steps from no license to a Delaware Level I wastewater operator license: meeting the requirements, passing the state exam, applying to the Board of Certification, keeping your license active and what operators earn. Every requirement links to the Delaware Department of Natural Resources and Environmental Control (DNREC), its Board of Certification for Wastewater Operators or the licensing regulation, 7 DE Admin. Code 7204.
DNREC makes the final eligibility determination. Check with DNREC before you apply.
Why it matters
DNREC says all wastewater treatment facilities in Delaware must be operated under the direct supervision of a Delaware Licensed Wastewater Operator.
Each facility must be under a licensed operator in Direct Responsible Charge (DRC) whose license level matches or is higher than the facility's class. No one may do the duties of a licensed operator without a Delaware Wastewater Operator's License.
On-site wastewater disposal systems designed for less than 2,500 gallons per day are exempt, and DNREC may exempt some other small facilities. DNREC tells the owner when a facility is exempt.
To be issued a license, you must be working at a Delaware wastewater treatment facility or have a written job offer from one.
Delaware licenses operators at Level I, II, III and IV. Level IV is the highest. DNREC also issues Temporary and Operator-In-Training (OIT) licenses.
DNREC rates each wastewater treatment facility Class I to IV with a point system: Class I is 11 to 30 points, Class II 31 to 55, Class III 56 to 75 and Class IV 76 or more.
The rule covers wastewater treatment facilities and sets no separate collection system license.
Operating more than one facility needs the Board's approval through a multi-plant application, and generally at least a Level II license.
Step 1
Level I needs a high school diploma or equivalent and one year of acceptable operating experience in a wastewater treatment facility.
Experience counts when it comes from satisfactory work. The Board may give partial credit for maintenance, laboratory or other water or wastewater work.
The Board reviews your education, experience and knowledge, and may also ask for evidence of good character and dependability.
Step 2
If you are working (or have a job offer) as a wastewater operator in Delaware but have not yet passed the exam or met the requirements, the Board may recommend a Temporary Level I OIT license. You work only under the immediate direction of a licensed operator and must pass the state exam within two years. It is valid for two years.
If you pass the exam but do not yet meet the experience or education requirement, you may receive an Operator-In-Training (OIT) license with the Board's approval.
An OIT license holder may be in Direct Responsible Charge of a facility only on the Board's recommendation, temporarily, for up to two years.
Step 3
In Delaware you pass the exam first, then apply for the license. Apply for the exam in Digital DNREC, DNREC's ePermitting system, under Division of Water License, Surface Water Discharges. If you cannot use Digital DNREC, call the Division of Water at 302-739-9116.
The exam is given four times a year, in February, May, August and November. The 2026 dates are February 13, May 15, August 14 and November 13.
Apply and pay at least 14 calendar days before the exam. The exam fee is $100, paid by credit card, and is not refundable.
Once you are assigned to a session, the exam is not rescheduled. If you miss it, you receive a zero and must apply again.
Step 4
After you pass, apply for the license in Digital DNREC. Upload your educational transcripts and the required documents, and name your employer or the employer that offered you a job.
The license application fee is paid by credit card and is not refundable. DNREC's fee page lists the current amount; DNREC updated many fees in December 2025, so check it before you pay.
DNREC forwards your application to the Board of Certification for review and emails you the result. Your exam result stays valid for three years.
Licenses are issued for two years and are emailed to you. If your employer changes, update it in Digital DNREC right away.
Step 5
To renew every two years, show at least 20 hours of approved training from those two years. At least 10 hours must be directly about wastewater facility operation or maintenance; up to 10 can be indirectly related courses the Board approves.
Upload proof of each course in the Water Continuing Education tab of your Digital DNREC account. DNREC staff must approve your hours before you can renew, so DNREC encourages submitting them at least 30 days before your license expires.
The list of approved courses is in that same tab. You cannot repeat a directly related course in back-to-back renewal periods. Licensed operators who attend a Board meeting receive continuing education credit.
Digital DNREC emails a reminder about 60 days before your license expires, but you are responsible for renewing on time even without it. Renewal fees are not refundable; see DNREC's fee page for the amount.
A license not renewed by its expiration date is invalid, and working without a valid license is unlawful. You can still renew within two years by meeting the training requirement and paying a late fee. After two years, you must apply again and pass the exam, and you get a new license number.
Exam day
The Board of Certification, or someone it designates, prepares Delaware's written exams. There is a separate exam for each level, made up of multiple-choice and true/false questions. You need 75% or higher to pass.
DNREC gives the exam in person on an electronic testing system. Arrive at least 20 minutes early with a photo ID and your Digital DNREC login and password.
Results come by email. Exams are not returned, but you can ask to review your results with a Board member or its designee.
To retake, submit a new application and fee. After failing the same level twice in a row, you must complete an approved exam review course before taking that level again.
Delaware's exams are written state exams prepared by the Board of Certification or its designee, and the DNREC pages we could read do not say how many questions they have, how long you get or whether a formula sheet is provided. Operator Master's free practice questions, timed practice exam and math help are built on the WPI exam format and the WPI formula table, so use them for general wastewater knowledge and math, and ask DNREC's Division of Water Licensing about the Delaware exam. Operator Master is an independent study tool, not the official exam.
Pay
The median pay for water and wastewater treatment plant and system operators in Delaware was $64,940 a year ($31.22 an hour) in 2025, compared with $60,020 nationally. One in ten earned $48,160 or less, and one in ten earned $84,360 or more.
These federal figures cover drinking water and wastewater operators together, at every level. Pay for a new operator is usually nearer the low end.
Moving up
Every level also needs a passed exam for that level within the last three years. College-level education the Board approves can replace operating experience year for year, but you still need at least one year of actual experience for Level I and two years for Levels II to IV, and education never replaces DRC experience. One year of DRC experience can replace one year of college. The Board decides training-course substitutions case by case.
From another state
The Board may recommend a license without an exam, at a comparable level, if you hold a current certificate or license from another jurisdiction whose requirements are at least as high as Delaware's.
Apply for the license in Digital DNREC and answer Yes to applying under reciprocity; you skip the exam application. DNREC's board page suggests describing your current state's licensing requirements and your wastewater experience.
You still need to be working at, or have a job offer from, a Delaware wastewater treatment facility.