Median Pay by Area
- Fort Wayne
- $61,240 a year
- Indianapolis-Carmel-Greenwood
- $58,530 a year
- Evansville
- $55,050 a year
- Lafayette-West Lafayette
- $54,720 a year
- South Bend-Mishawaka (IN-MI)
- $53,490 a year
Indiana wastewater operators
The steps from no certificate to an Indiana Class I wastewater treatment plant operator certificate, how to apply to IDEM and take the exam at Ivy Tech, the education and experience each class needs, how to renew and what operators earn. Every requirement links to the Indiana Department of Environmental Management (IDEM), Indiana's certification rule (327 IAC 5-23) or the Indiana law it follows.
IDEM makes the final eligibility determination. Check with IDEM before you apply.
Why it matters
Indiana law says no one may operate a wastewater treatment plant, public or private, unless IDEM has certified the operator in responsible charge, and no one may perform the duties of an operator in responsible charge without being certified.
The plant's owner must place each plant under the direct supervision and responsible charge of a certified operator whose class matches the plant's class, and must tell IDEM who that operator is.
IDEM issues the certificates. The law and rule call the credential a certificate; IDEM's pages also call it a license, and IDEM says the two words mean the same thing.
Indiana has ten wastewater operator classes. Municipal (nonindustrial) plants that mainly treat sanitary wastewater use Class I-SP for waste stabilization ponds, then Class I, II, III and IV by the plant's design population equivalent: under 2,000, 2,000 to under 10,000, 10,000 to 40,000 and over 40,000.
Industrial treatment plants use Class A-SO (solids removal, oil separation, pH adjustment or cartridge filtration only), then Class A, B, C and D by treatment type and size.
A higher class also covers lower plants. For example, a Class IV operator may operate Class I-SP, I, II, III and IV plants plus Class A-SO and A plants, and a Class D operator may operate Class A-SO to D plants.
You can take an exam before you have the education and experience and become an apprentice for that class. An apprentice certificate lasts up to six years, and an apprentice cannot be the operator in responsible charge of a plant.
Step 1
Class I (and industrial Class A) needs a high school diploma or equivalent and nine months of full-time acceptable experience at a wastewater treatment plant. Class I-SP and Class A-SO need three months.
Acceptable experience means hands-on operation, maintenance, management or supervision of a wastewater treatment plant, gained under the supervision of a certified operator.
Full time means at least 1,560 hours a year at the plant. Part-time experience counts at a proportionally lower rate.
Short on education or experience? IDEM can make substitutions. For Class I, up to three of the nine months can come from one college semester, 16 college credit hours, 240 contact hours, 24 CEUs or a degree, and extra plant experience can make up for missing high school.
Step 2
Without plant experience yet, you can apply as a Wastewater Apprentice using IDEM's short-form apprentice application and take the same exam. IDEM says passing may make it easier to get a job in the industry.
To move from apprentice to certified operator, meet the education and experience for the class you passed, earn the apprentice contact hours the rule sets for each year, and apply to IDEM within six years of passing. After six years, you must pass the exam again.
If a plant loses its certified operator, the owner can ask IDEM for a provisional certificate for someone who already meets the education and experience. It is valid for 90 days, can be extended to no more than one year in total, and cannot be renewed.
Step 3
Print and complete the Application for Wastewater Treatment Plant Operator Certification Examination (State Form 47289). IDEM does not take applications electronically.
Mail it with the $30 application fee and your supporting documents to IDEM Accounts Receivable, 100 N. Senate Ave., Room 1340, Indianapolis, IN 46204-2251. The fee is not refundable, and checks are made payable to the Indiana Department of Environmental Management.
Your supervisor signs the application. Use a separate application and fee for each exam; you may sit for one municipal and one industrial exam on the same day.
If you qualify, IDEM sends an eligibility letter listing the Ivy Tech testing locations. The letter is good for 180 days. If you do not qualify, IDEM staff will explain what documentation, education or experience is still needed.
Step 4
IDEM publishes a study guide for each exam: Classes I and A, Class II, Classes III and IV, Classes B, C and D, Class I-SP and Class A-SO. It recommends starting with its Wastewater Operator Certification Exam Book List.
IDEM's Formula Sheet will be provided for your use during the exam, and any of its formulas may be used on any class of exam. Math is about ten percent of each exam.
IDEM strongly encourages a training course before the exam and posts a list of course providers. IDEM does not recommend or endorse any one provider.
Step 5
Ivy Tech gives IDEM's exams by computer on most business days at about 25 locations. After IDEM approves you, schedule on the Ivy Tech website (choose Schedule Now, then Non-Student Login) or call the testing center you want.
Ivy Tech charges its own $45 fee before the exam. Pay it to Ivy Tech; do not send it to IDEM.
Bring your exam admission letter to your appointment. If you cannot make it, you may ask IDEM in writing for one postponement before the approval letter expires. Missing the exam without a postponement counts as a failed exam.
Step 6
Most certificates must be renewed every three years; the expiration date is on your card. A new certificate after an exam may have a shorter first period. IDEM mails a renewal notice at least 30 days before it expires.
Renew before July 1 of the year your certificate expires, by returning the signed renewal notice or online (online renewal opens May 1), with the $30 renewal fee.
Each renewal period, Class I-SP and A-SO operators need 8 contact hours, Class I, A, II and B need 15, and Class III, C, IV and D need 30. At least 70% must be technical. A contact hour is an approved session of at least 50 minutes.
Hours must be reported to IDEM within 90 days, and late hours do not count. IDEM posts a monthly list of the hours on record for each operator so you can check yours. A course repeated in the same renewal period earns no credit.
With an expired certificate you may not work as an operator in responsible charge. If you go more than one year past expiration without renewing, you must pass the exam again.
Exam day
IDEM keeps its own question bank. The Class I-SP and A-SO exams have 50 questions and the other eight exams have 100, all multiple choice. You have three hours once testing begins.
A score of 70% passes. Ivy Tech gives you a preliminary score before you leave, and IDEM then sends your official result in writing. If you pass, IDEM mails your certificate and card.
IDEM's Formula Sheet is provided at the exam. You choose the right formula for each math question.
If you do not pass, reapply with a new application, or sign and return the score letter IDEM sends, with a new $30 fee.
After three failed attempts, you must attend and pass an approved exam preparation class with at least 8 hours of technical wastewater content before trying again. IDEM lists providers and also teaches its own class.
Anyone caught cheating is treated as failing and cannot take a wastewater certification exam for two years.
IDEM's certification exams are Indiana exams: IDEM draws the questions from its own question bank and hands out its own formula sheet at the exam. 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 they cover general wastewater treatment knowledge and math, not IDEM's exam questions, formula sheet or Indiana rules. Use IDEM's study guides, book list and formula sheet as your main guide. 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 Indiana was $53,540 a year ($25.74 an hour) in 2025, compared with $60,020 nationally. One in ten earned $40,590 or less, and one in ten earned $75,290 or more.
These federal figures cover drinking water and wastewater operators together, at every class. Pay for a new operator is usually nearer the low end.
Moving up
Industrial Classes A-SO, A, B, C and D need the same as Classes I-SP, I, II, III and IV, in that order. Responsible charge experience at industrial plants also counts: Class B, C or D for Class III, and Class C or D for Class IV. In Class III, IV, C and D plants, supervising a major section of the plant or an operating shift counts as responsible charge experience. IDEM's substitution policy lets extra education, experience or responsible charge experience make up some shortfalls.
From another state
IDEM may issue a certificate in a comparable class without an exam to someone certified in another state or U.S. territory, if that state's requirements are not lower than Indiana's and do not conflict with them, and that state gives the same privilege to Indiana operators.
Apply on the Application for Wastewater Treatment Plant Operator Certification by Reciprocity (State Form 47290) with the $30 nonrefundable fee and a copy of your current certification. The form asks whether you earned it by written exam, and your supervisor signs it.
A certificate issued by reciprocity is renewed the same way as any Indiana certificate, including the continuing education.