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What is a Public Water Supply?

Grand Traverse Commons water tower with blue sky background
Environment, Great Lakes, and Energy

What is a Public Water Supply?

Types of Public Water Supplies

“A classification system for public water supplies is established under the Michigan Safe Drinking Water Act, 1976 PA 399, as amended (Act 399), being MCL 325.1001 et seq. (Act 399 Rules), and the administrative rules promulgated thereunder, being R 325.10101 et seq. Public water systems are classified by the population served or the nature of their customer base.” 

Classification Description Examples
Type I Community Water Supply Provides year-round service to not less than 25 residents OR not less than 15 living units. Municipalities, Apartments, Condominiums, Nursing Homes, Mobile Home Parks
Type II Nontransient Noncommunity Public Water Supply Serves not less than 25 of the SAME people for at least six months per year. Schools, Industries, Places of Employment
Type II Transient Noncommunity Public Water Supply Serves not less than 25 people OR not less than 15 connections for at least 60 days per year. Hotels and Restaurants (with less than 25 employees), Campgrounds
Type III Public Water Supply Anything not considered a Type I or Type II water supply; serves less than 25 people AND 15 connections, or operates for less than 60 days per year. Small Apartment Complexes and Condominiums, Duplexes, All Others

Type II Noncommunity Water Supplies are also classified according to their water production. Type IIa Water Supplies have an average production during the maximum month equal to or greater than 20,000 gallons per day. Type IIb Water Supplies produce less than 20,000 gallons per day during the peak month.

A Drinking Water Supply Types infographic with additional information is provided by the Michigan Department of Health and Human Services and EGLE.

**Ownership or operation of multiple waterworks systems in the same general location is critical to determining classification. See Rule 503 of the Act 399 Rules and additional information in DWEHD-399-013 – Classification of Public Water Supplies.