New Hampshire wastewater operators
The steps from no certificate to a New Hampshire Grade I wastewater treatment plant operator certificate, how to qualify for and pass the exam, how to keep your certificate active and what operators earn. Every requirement links to New Hampshire's operator certification rules, Env-Wq 304, or the state law behind them, RSA 485-A.
NHDES makes the final eligibility determination. Check with NHDES before you apply.
Why it matters
New Hampshire law says wastewater treatment plants may be operated only by certified operators. The New Hampshire Department of Environmental Services (NHDES) certifies them.
Plant owners must make sure everyone doing important operating work is certified. That includes removing pollutants to meet permit limits, maintaining pumps, valves and process equipment, running chemical feeders, doing lab analysis, keeping required records and watching SCADA screens or gauges that track the process.
Each plant must name an operator in responsible charge (OIRC) and a back-up OIRC. Both must be certified at the plant's grade or higher.
These rules cover wastewater treatment plant operators and have no separate collection system certificate. Work in wastewater collections can count toward part of the experience you need.
There are four grades of wastewater operator certificate, Grade I to Grade IV, matching the four grades of wastewater treatment plants. Grade IV is the highest.
A Grade I operator may supervise Grade I plants. Each higher grade covers plants of that grade or lower, so a Grade IV operator may supervise any plant.
NHDES grades each plant by adding points for its size and treatment processes: 30 points or fewer is Grade I, 31 to 55 is Grade II, 56 to 75 is Grade III and more than 75 is Grade IV.
Each grade also has an operator-in-training (OIT) status for people who pass the exam before they have all the experience that grade needs.
Step 1
Grade I and Grade II need a high school diploma or a High School Equivalency (HSE) certificate.
Grade III and Grade IV also need 2 years of relevant education after high school. A bachelor's degree in sanitary engineering, environmental technology or science, water treatment or wastewater treatment counts as 4 years, and an associate degree in those fields as 2 years. Each 30 semester hours (or 45 quarter hours) in those programs counts as one year.
In other relevant technical and science fields, such as natural sciences or non-sanitary engineering, a bachelor's degree counts as 3 years and an associate degree as 1.5 years. Any other bachelor's degree counts as 2 years and any other associate degree as 1 year.
You can ask to replace one year of the college requirement with two years of operating experience, one year as an OIRC at a Grade II or higher plant, or approved operator training or relevant military training. Anything you use in place of education cannot also count as experience.
Step 2
Operating experience means doing or supervising operating duties at a wastewater treatment plant, plus certain related experience.
You need no experience to take the Grade I exam. Grade II needs 1 year before the exam, or a one-year certificate in wastewater or environmental technology, or a relevant associate degree. Grade III needs 2 years at a Grade II or higher plant, and Grade IV 3 years at a Grade III or higher plant.
At least half of the experience a grade requires must be hands-on at a wastewater treatment plant. For the rest, you can ask to count related work such as wastewater collections, water distribution, plumbing, electrical, instrumentation, lab, utility construction, facilities maintenance or public works, relevant college year for year, or approved wastewater training courses and conferences.
Step 3
You can take a grade's exam with less experience than the full grade requires, as long as you can gain the rest within 3 years. If you pass, you hold OIT status for that grade.
You become fully certified once NHDES receives written confirmation from your supervisor that you have finished the experience. If you do not finish within 3 years, you go back to your earlier grade.
Step 4
Apply at least 6 weeks before the exam date with the online Wastewater Treatment Operator Certification Exam Application. The same application is used to move up to a higher grade.
Include proof of high school graduation or HSE if you have no college, transcripts for any college, and proof of any specialized operator training you want counted.
The application fee is $50. If you fail the exam, one retest at the same grade is included at no extra cost.
By signing, you confirm your information is true and agree to follow the rules, including New Hampshire's wastewater operator code of ethics. You are told in writing whether you are eligible, and if not, why.
Step 5
NHDES tells you your result as soon as it can, and no later than 60 days after the exam.
Once you pass and meet the education and experience for the grade, NHDES issues a certificate showing your grade. It must be displayed in the office of the plant where you work.
Keep your mailing address, daytime phone and email up to date with NHDES, and tell NHDES in writing when you are named OIRC or back-up OIRC or leave that role.
Step 6
Certificates are renewed every two years. Each one lasts until December 31 or June 30, no more than 2 years from issue, and expires on the date printed on it.
Submit the online renewal application no later than one state business day before your certificate expires. Include copies of your training certificates from the past two years and the renewal fee set by RSA 485-A:7-c.
Every grade needs 20 training credit hours (TCHs) in the two years before expiration; a Grade I OIT needs 10. One TCH is one hour of qualifying training. At least half must be directly about wastewater treatment processes or maintaining them.
Extra hours can carry forward to the next renewal period only: up to 10 TCHs, or 5 for a Grade I OIT.
Courses count when NHDES offers them, when a statewide or regional professional association of wastewater professionals offers them, or when NHDES has approved them.
If you do not apply to renew in time, your certificate expires. To be certified again, you apply and pass the written exam again.
Before your certificate expires, you can ask in writing to go inactive for up to 2 years. You cannot do any plant operating work while inactive. To reactivate, send a renewal application, the renewal fee and proof of 40 TCHs.
Exam day
NHDES prepares a written exam for each grade to test your knowledge, ability and judgment.
NHDES gives the exams at least twice a year, at places and times it sets.
You pass with a score of 70% correct or higher.
If you fail, your one free retest must be at one of the next 2 scheduled exams. Tell NHDES in writing at least 6 weeks before that exam, with any changes to your application.
You can arrange to review your failed exam at the NHDES office, as long as the review is more than 60 days before your retest.
NHDES writes and gives its own written exams. The rules and laws used for this guide do not say how many questions they have, how long you get or whether a formula sheet is handed out. 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 NHDES what the New Hampshire exam covers. 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 New Hampshire was $62,940 a year ($30.26 an hour) in 2025, compared with $60,020 nationally. One in ten earned $49,170 or less, and one in ten earned $81,290 or more.
These federal figures cover drinking water and wastewater operators together, at every grade. Pay for a new operator is usually nearer the low end.
Moving up
Every grade needs a high school diploma or HSE certificate. The first figure is the total experience for full certification; the figure in brackets is what you need before the exam. At least half of the experience must be hands-on at a wastewater treatment plant, and related work, college or approved training can make up the rest.
From another state
If you hold a wastewater treatment plant operator certificate from another state or jurisdiction and are seeking work in New Hampshire, you can ask to be certified at a comparable grade without taking the written exam.
Your certificate must still be valid and earned by passing a written exam, you must never have had a certificate revoked or suspended in any state, and the other jurisdiction's requirements must not conflict with or be less strict than New Hampshire's.
Reciprocity is not available for Grade IV.
Apply online with the Wastewater Treatment Operator Certification Reciprocity Application. Include a copy of your certificate or license, a copy of the other jurisdiction's certification rules, proof of your education and training, and the fee set by RSA 485-A:7-c.
