Free Practice Questions for IL Water/WW Operator

A score of 70 or higher passes every Illinois EPA drinking water and wastewater operator certification examination. The municipal wastewater exams (Classes 1, 2, 3 and 4) and the voluntary Collection System exam each contain 100 multiple-choice questions with a 3-hour maximum, running 9:00 a.m. to 12:00 p.m. The facility-specific industrial Class K exam has 15 questions (5 multiple choice on basic wastewater mathematics plus 10 short-answer/essay questions about the applicant's own facility), and the general Class R water remediation exam has 14 questions (7 multiple choice and 7 short answer). Drinking water exams for Classes A through D run 9:00 a.m. to 2:00 p.m. under a 5-hour maximum; the Illinois EPA does not publish a question count for them.

Under 35 Ill. Adm. Code Part 380, Illinois classifies municipal wastewater operators into four tiers: Class 1 (all domestic treatment systems with a design average flow of 1.0 MGD or more, excluding lagoon and primary treatment systems; 6 years of experience); Class 2 (activated sludge systems under 1.0 MGD DAF; 4 years); Class 3 (fixed-film processes and Imhoff tank systems under 1.0 MGD DAF plus all primary treatment systems; 2 years); and Class 4 (aerated and non-aerated lagoon treatment systems; 1 year). Industrial facilities require a facility-specific Class K certificate, and petroleum groundwater remediation systems may instead use the general Class R certificate. A separate voluntary Collection System Operator certificate covers sewer operation and maintenance.

Under 35 Ill. Adm. Code Part 681, effective April 1, 2014 in place of the repealed Part 680, Illinois classifies drinking water operators into Classes A through D by treatment complexity. Class A covers coagulation/sedimentation, lime softening, UV disinfection, pathogen removal or inactivation, and membrane filtration (5,340 hours of experience, at least 2,670 of them hands-on). Class B covers aeration and filtration other than membrane filtration plus ion exchange (5,340 hours, at least 2,670 hands-on). Class C covers chemical feed such as chlorination or fluoridation (1,780 hours, at least 890 hands-on). Class D covers pumpage, storage and distribution (890 hours, at least 445 hands-on).

Illinois candidates may sit for a certification examination before completing the required operating experience. A drinking water candidate who scores 70 or higher becomes an Operator in Training for that class; the OIT classification is valid for six years, cannot be renewed, carries no renewal training requirement, and does not qualify the holder to serve as the Responsible Operator in Charge of a community water supply. If full certification is not obtained within those six years, the exam process must start over. On the wastewater side, a passing score confers Operator-In-Training status that stays effective for five years from the date of examination, and an Operator-In-Training cannot serve as the properly certified operator for a facility.

Drinking water certificates and wastewater Class 1 through 4 certificates are both renewed every three years. Wastewater Classes 1 and 2 require 30 hours of approved continuing education with at least 20 technical hours; Classes 3 and 4 require 15 hours with at least 10 technical hours. Drinking water Classes A and B require 30 hours with at least 20 technical hours and no more than 10 non-technical hours; Classes C and D require 15 hours with at least 10 technical hours and no more than 5 non-technical hours. Class K, Class R and Collection System certificates carry no continuing education requirement.

A facility-specific Class K certificate is issued only for the industrial wastewater treatment or pretreatment facility for which the operator wrote the examination, and is tied to that permit and location. An operator seeking to run more than one such facility must pass a separate Class K examination for each, and must re-take the exam if the facility modifies its treatment process. Class K certificates are valid for 5 years with no renewal process and no continuing education units: the operator must re-take and pass the examination. Class K and Class R certificates are also not eligible for reciprocity from another state.

The Illinois EPA administers examinations monthly at regional sites. The 2026 wastewater schedule uses the Des Plaines and Rockford regional offices, Illinois EPA headquarters in Springfield, the Marion regional office, and the Environmental Resources Training Center (ERTC) at Southern Illinois University Edwardsville. The 2026 drinking water schedule uses those same sites plus the Champaign regional office and two Illinois Rural Water Association conference sittings. Candidates must submit an examination request form at least 30 days before the desired test date, then contact the testing site to reserve a seat. There are no fees for wastewater operator certification; drinking water charges a $10 non-refundable exam request fee, a $30 certification application review fee, and a $10 renewal fee.