Missouri regulations: Drinking water

Many businesses, especially those located in rural areas, rely on a well for drinking water. Because of Missouri’s karst geology, with limestone sinkholes and caves, water and contaminants can travel very quickly through the ground and cover great distances. It is very important to monitor and regulate drinking water to prevent the spread of waterborne diseases and protect people from exposure to dangerous pollutants.

If a business using a well for drinking water has 15 or more connections to that well, such as a campground or a motel, it is considered a public drinking water system. Also considered public water systems are those businesses that serve an average of 25 consumers a day for at least 60 days out of the year. This could apply to restaurants, service stations, day care centers or resorts.

The Missouri Department of Natural Resources (MDNR) is authorized to enforce regulations put in place by the Safe Drinking Water Act. Businesses affected by the regulations are required to have a permit from the MDNR to dispense water. Along with the permit application, businesses must provide documentation on system reliability, safety and construction (engineering studies) as well as an emergency operating plan. The system must be monitored and tested on an annual basis. A certified operator may be required.

The MDNR can assist businesses with questions about backflow prevention and cross-connection control, construction permits, consumer confidence reports, drinking water standards, financial assistance, lead contamination, public water supply testing, water system assessments and source water assessment and protection.

Operator Certification (for distribution and/or treatment of water supplies)

Public drinking water systems are also required to have certified operator who maintains the system day to day and ensures that the water meets at least the minimum standards established by the regulations. Training for distribution certification and for treatment certification must be completed every three years. Get Operator Certification information online from MDNR.

Who should apply for a permit?

  1. Does the business provide drinking water to 15 or more connections?
  2. Does the business provide drinking water to an average of 25 people per day for at least 60 days per year?
  3. Are water lines being constructed to connect to an existing community water system?
  4. Is a new well being drilled for a water supply, irrigation or a heat pump?
  5. Is a well being drilled to inject fluid into the ground or groundwater?

A “YES” answer to any of these questions may indicate that the business is required to obtain a permit from the MDNR. Contact the Public Drinking Water Branch or your MDNR Regional Office.


For more information on wastewater permit requirements, see MDNR’s Environmental Permits and How to Obtain Them).