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Choose your certification
How Connecticut classifies drinking-water operators
Connecticut splits certification between two agencies. Drinking water runs through DPH under RCSA 25-32: Water Treatment Plant Operator Classes I through IV, Distribution System Operator Classes I through III, and a Small Water System certificate, each also available…
Full breakdown in the FAQ below.
Choose your Connecticut certification
Water Treatment Plant Operator (Classes I–IV)
Connecticut Class I Water Treatment Practice Test
Connecticut's entry treatment certificate uses the WPI Water Treatment Class I exam, computer-based at PSI. One year of experience at a Class I or higher plant (or take it as an Operator-in-Training after the 15-credit Water Management certificate, no experience needed).
DPH · WTP Class IIConnecticut Class II Water Treatment Practice Test
The WPI Water Treatment Class II exam. Two years of experience operating a Class II or higher plant (or direct responsible charge of a Class I plant); up to one year substitutable with postsecondary education, and certified wastewater operators can credit half their wastewater time.
DPH · WTP Class IIIConnecticut Class III Water Treatment Practice Test
The WPI Water Treatment Class III exam. Three years of experience at a Class III or higher plant or DRC of a Class II plant, with up to two years substitutable by education.
DPH · WTP Class IVConnecticut Class IV Water Treatment Practice Test
Connecticut's highest treatment certificate, using the WPI Water Treatment Class IV exam. Four years of experience at a Class IV plant or DRC of a Class III plant, up to three substitutable by education.
Small Water Systems
Connecticut wastewater practice tests
Connecticut DEEP certifies wastewater treatment operators in Classes I through IV using WPI exams (computer-based since 2026, one application window per year). The ladder is education-heavy: from a mandatory 9-CEU basic course at Class I up to 135 CEUs at Class IV. Certificates never expire but go inactive two years after leaving the field.
Connecticut Class I Wastewater Practice Test
Connecticut's entry wastewater certificate: one year of experience plus a mandatory commissioner-approved basic wastewater course of at least 9 CEUs (about 90 contact hours), with no substitutions allowed at Class I. WPI exams delivered computer-based, $240 application plus $114 exam fee.
DEEP · Class IIConnecticut Class II Wastewater Practice Test
Class II requires three years of experience at a Class I or higher facility plus 30 CEUs of higher education (at least 18 directly wastewater-related). Education can substitute for up to half the experience at Classes II through IV.
DEEP · Class IIIConnecticut Class III Wastewater Practice Test
Class III requires four years of experience at a Class II or higher facility plus 90 CEUs (at least 27 wastewater-related). Direct-responsible-charge time can substitute for up to 15 CEUs.
DEEP · Class IVConnecticut Class IV Wastewater Practice Test
Connecticut's highest wastewater certificate: four years at a Class III or IV facility including two years of direct responsible charge, plus 135 CEUs. No OIT path exists at Class IV.
Connecticut licenses distribution operators in Classes I through III, and DPH's official exam crosswalk runs one step offset from the national numbering: DS Class I sits the WPI Distribution Class 2 exam, DS II sits Class 3, and DS III sits Class 4. The WPI Class 1 exam is used for Connecticut's Small Water System certificate (on the Drinking Water tab). Each card below links the correct exam for the Connecticut class named on it.
Connecticut Class I Distribution Practice Test
Heads up: Connecticut's DS Class I exam is the WPI Water Distribution Class 2 exam per DPH's official crosswalk, so this is the right test. One year of distribution experience required.
DPH · DS Class IIConnecticut Class II Distribution Practice Test
Connecticut's DS Class II uses the WPI Water Distribution Class 3 exam. Two years of distribution experience, up to one substitutable with postsecondary education.
DPH · DS Class IIIConnecticut Class III Distribution Practice Test
Connecticut's highest distribution certificate uses the WPI Water Distribution Class 4 exam. Four years of experience, up to three substitutable by education.
Connecticut does not issue a wastewater collection license. Collection systems fall under the treatment plant's chief operator, and DEEP's guidelines recommend (but do not require) voluntary collection certification through NEWEA. If your work involves collections, the national collection-system practice tests on the Collections hub cover that material.
About the Connecticut operator exams
Operator certification in Connecticut covers several disciplines — drinking water, wastewater, distribution, and collections — which may be handled by the same agency or by separate programs (drinking water is administered by CT DPH (drinking water) and DEEP (wastewater) — Operator Certification). The exact certification structure, exam format, levels, and continuing-education requirements vary by discipline and change over time, so always confirm the current scope and eligibility directly with the certifying agency. Our practice content focuses on the underlying technical material — the same operating principles, math, regulations, and process knowledge that show up on water and wastewater operator exams nationwide.
Frequently asked questions
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Disclaimer: WaterOperatorPracticeTest.com is an independent study aid. We are not affiliated with CT DPH (drinking water) and DEEP (wastewater) — Operator Certification or any state primacy agency. Always confirm current exam requirements with your state's certification body.