Drinking Water

Public Water Systems are legally defined as entities that provide water to 25 or more people for more than 60 days a year or have 15 or more service connections. In Montana this includes cities, towns, water districts, subdivisions, HOAs, campgrounds, restaurants, bars and other businesses. The Public Water Supply Bureau at DEQ regulates public water systems in Montana to ensure that the water being served meets federal Safe Drinking Water Act and state laws and regulations. Private wells are not regulated under these regulations.  

Rivers, lakes, springs and wells provide water to PWS that are often treated before serving to the public. The number of people served, the type of source water, and type of contaminants determines the frequency of drinking water testing.

Compliance and reporting is critical to maintaining Montana’s public water supply. DEQ conducts a variety of inspections and requires mandatory reporting to ensure compliance and protection of public health.

• If you are a certified operator or are looking to become certified, visit our Operator Certification page for more information on forms, monitoring schedules, checking your CECs, and other applicable requirements.
• Summary data regarding compliance for all public water supply systems in Montana can be viewed in Montana's 2023 Annual Public Water System Compliance Report
•  Locate your source water assessment report
•  Find information on private wells and septic systems here: Water Resources