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Public drinking water systems

Wisconsin has more public drinking water systems than anywhere else in the nation. Many small businesses, including hotels, restaurants and manufacturing facilities, are public water systems. These public water systems are essential for providing safe water to the citizens of the state. State and federal regulations are in place to help public water system owners and operators do just that, so they can provide this vital resource to their valued customers or employees and enjoy business success. Refer to the questions below to get started!

Is my business a public water system?

The Wisconsin Department of Natural Resources (DNR) and the U.S. Environmental Protection Agency (USEPA) define a "public water system" as a system for the provision to the public of piped water for human consumption, if such a system has at least 15 service connections or regularly serves an average of at least 25 individuals daily at least 60 days out of the year. "Serving" water means that you have water available for drinking regardless of whether the water is actually being consumed. If your facility provides drinking water and fits this definition, you have a legal responsibility to monitor the quality of your water. In Wisconsin, the DNR's Bureau of Drinking Water and Groundwater works with public water system operators to meet safe drinking water regulations. If your business gets its water from a municipality, the municipality is responsible for the water, not your business. You will know if you are on a municipal system if you get a utility bill. However, if your business has a private well that provides water to your customers and/or employees, you are responsible for the water quality and will be subject to regulations.

There are four types of public water systems in Wisconsin. Community water systems serve residences. They are public water systems that serve at least 15 service connections used by year-round residents or regularly serve at least 25 year-round residents. Any public water system serving 7 or more homes, 10 or more mobile homes, 10 or more apartment units, or 10 or more condominium units is a community water system unless information is available to indicate that 25 year-round residents will not be served. Non-community water systems are public water systems that serve people at places other than where they live. The type of system you operate determines your regulatory obligations, so it is very important to accurately identify which type of system your business falls under. See the table below for definitions.

Community water systems
(serve people where they live):
Non-community water systems
(serve people at work, school, food and entertainment establishments, etc.):
Municipal community (MC) water systems have 15 or more service connections, or serve a community of at least 25 residents for at least 6 months of the year. MC systems are owned by a city, town, village, or other government entity. Non-transient non-community (NN) water systems serve at least 25 of the same people for at least 6 months of the year. NN systems include schools, day care centers, factories, or businesses with 25 or more employees.
Other-than-municipal community (OTM) water systems have 15 or more service connections, or serve a community of at least 25 residents for at least 6 months of the year, but are not owned by municipalities. OTM systems include mobile home parks, subdivisions, apartment buildings and condominium complexes. Transient non-community (TN) systems serve at least 25 people, but not necessarily the same people, for 60 days a year or more. TN systems include motels, restaurants, taverns, campgrounds, parks and gas stations.

The DNR's Drinking Water Program has An Operator's Handbook for Safe Drinking Water (DG-056) available for owners and operators of OTM and NN systems. This handbook outlines your legal obligations as an owner/operator of a public water system and will help you provide safe and healthy drinking water to your customers and employees.

Do I need a certified operator?

Municipal community (MC), other-than-municipal (OTM) community and non-transient non-community (NN) water systems are required to have a certified operator to manage their system; whereas, transient non-community (TN) systems are not. The operator may be a member of your staff but could also be a hired contractor.

Operators must have a certificate issued by the DNR which qualifies them to work at a water system. Operators with a general water system certification (subclass O) or a municipal waterworks certification (D, G, or S subclass) are qualified to be certified operators for OTM and NN systems.

Basic requirements for certified operators:

  • High school diploma or general equivalency (with the exception of those who had at least two years of experience before December 1, 2000).
  • Score of at least 75% on the certification exam.
  • Continuing education training and certification renewal every three years.

Water system owners will want to make sure their operators maintain current certifications. Also, be sure to notify the DNR if you change operators.

If your water system operator needs to take an exam or renew certification, don't delay! Exams are offered twice a year and six hours of continuing education are needed for certification renewal, so make sure to plan ahead. Continuing education courses are offered through the Wisconsin Rural Water Association (WRWA). The DNR has an operator certification event calendar available.

Visit small water system (OTM/NN) operator certification for in-depth information on taking the exam and renewing a certification as well as other helpful materials.

A list of Contract Certified Operator Services for Public Water Systems in Wisconsin is provided on DNR's website. If you are hiring a contractor instead of a permanent employee to be your certified operator, you will want to keep the following tips in mind:

  • Make sure the contractor possesses a certification in the right class/subclass appropriate for your water system. Check the operator certification lookup to verify certification.
  • Verify that the contractor has experience operating a water system similar to yours and ask for references.
  • Will a backup operator be available in case the primary one is unavailable?
  • How quickly can the operator respond to an emergency?
  • When hiring an operator, you will want to create a written agreement outlining the terms of the contract with information such as contract duration, compensation, time spent at your site, duties and responsibilities, insurance obligations, etc. If the contractor is not independent, you will want an official from the company employing the operator to also sign the agreement.
Constructing a new public water system: What approvals are required?

A new well must be properly located, constructed, installed and maintained in order to ensure safe drinking water. In addition, operating a well as part of your business requires technical, managerial and financial responsibilities to ensure your well and treatment systems are constructed to state standards and that you are in compliance with the federal Safe Drinking Water Act (SDWA). The DNR's plan review and capacity development programs are designed to help ensure you have the knowledge and resources you need to properly construct and operate your well and public water system.

Well construction: Well construction or reconstruction must be done by a licensed well driller. In addition, installing or replacing pumps, pitless adapters, accessory piping and pressure tanks must be done by a licensed pump installer. Information on requirements for well and pump professionals can be found on the license and registrations page.

Plan review: All new or modified municipal and other-than-municipal (OTM) public water systems require a public water system plan review before beginning construction. Some non-transient non-community (NN) systems also need a plan review if the system will be on a high-capacity property or will serve a school. Visit public water system plan review for details including plan guidelines, approval requirements and necessary forms. Plan review requirements depend on the type of project you are undertaking. Visit approval requirements for each type of project to learn about the specific requirements for your plan. Small public drinking water systems may find guidelines for other-than-municipal facilities, chemical feed equipment, iron filters, and softeners relevant to their operations. See the section on high-capacity wells for more information about those systems.

Capacity evaluation: All new community and non-transient non-community public water systems are required to conduct a capacity evaluation to demonstrate their technical, managerial and financial capacity to operate the water system. These systems must obtain a capacity approval form from the DNR. Visit the capacity development program for additional information and forms or review Wisconsin’s Capacity Development Program for New Public Water Systems (DG-058).

Please note: The Wisconsin Department of Safety and Professional Services (DSPS) regulates plumbing installations and requires a plumbing plan review for a variety of plumbing systems (both new and altered). View the plumbing plan review checklist for information on what to include when submitting a plan review, or contact DSPS at if you have questions about plumbing.

What well maintenance am I required to do?

As a public water system owner or operator, you are responsible for maintaining your facility in a safe and sanitary condition which will require periodic maintenance. You will need to use a state certified professional for well and pump maintenance and a master plumber for work on the distribution system. The following handbooks give a brief overview of your responsibilities as a public water system operator.

What is the procedure for start-up of a season public water system?

A seasonal public water system is defined as one that starts up and shuts down at the beginning and end of each operating season and depressurizes at least part of the water system at some point during the year. Businesses that commonly operate seasonal systems include ski chalets, summer resorts, campgrounds and restaurants that are only open part of the year. Beginning in 2016, a seasonal start-up procedure must be conducted each year prior to serving water to the public, and seasonal public drinking water systems must certify to DNR that the procedure has been completed.

To complete the start-up procedure, the owner or operator of the system must inspect and maintain well components, inspect the land around the well for potential bacterial contamination sources, correct any cross connections and flush the system until there is fresh water throughout the system. Once complete, the DNR must be notified, either through email or by mailing a paper certification form. The DNR's Seasonal Public Drinking Water System Start-Up Procedure (DG-079i) brochure provides more detailed instructions on the procedure and how to certify, as well as suggests for shutting down the system at the end of the season. Make sure to complete the start-up procedure every year before serving water to the public. Doing so will prevent a violation which would result in increased water sampling requirements.

How can I prevent contamination of the well water?

After maintaining a sanitary facility, the next factor in delivering safe water is activity on the land surface typically within about a quarter mile of your well. Avoiding contamination risks can be easy – and far less expensive than a new well or treatment. For many small system wells, the same protective techniques used by homeowners will work. See Better Homes and Groundwater (DG-070) for tips on protecting your water. Consider working cooperatively with neighboring businesses or landowners, or through a local government or business association, to remove or manage potential contaminant sources that may affect a number of wells serving small businesses in your community.

What if I am no longer using a well?

Unused wells can pose a significant risk to drinking water because they act as a conduit for surface contaminants to seep directly into groundwater. Therefore, you are required to property fill and seal a well on your property that is no longer in use. A well must be permanently filled and sealed within 90 days of being taken out of service. Some exemptions apply for high-capacity wells or wells used only seasonally.

A licensed well driller or pump installer is required for well filling and sealing. Contact lists for well drillers and pump installers, those who perform well filling and sealing, and well inspectors can be found on the contact lists. See the Answers to Your Questions on Well Filling and Sealing (DG-016). Once the well is completely filled and sealed by a licensed professional, the well driller or pump installer must report that the well filling and sealing has taken place by submitting an electronic Well Filling and Sealing Report using their online reporting system. Well filling and sealing has additional resources and details on how to file the report.

As a property owner, you will want to make sure any unused wells on your property have been properly filled and sealed and that the DNR has this information on file. Properly filling and sealing unused wells protects your drinking water and your investment. Verification of Abandoned Wells with No Filling and Sealing Report on File provides information on what to do if you aren't sure whether a well was properly filled and sealed.

What sampling and reporting are required?

The federal Safe Drinking Water Act (SDWA) sets limits on allowable levels for bacteriological and chemical contaminants in drinking water. These limits are called Maximum Contaminant Levels or MCLs. The SDWA also sets monitoring and reporting requirements. The DNR's Bureau of Drinking Water and Groundwater carries out the SDWA program in Wisconsin. Check the table of MCLs. A list of MCLs is also available in An Operator’s Handbook for Other Than Municipal and Nontransient Noncommunity Systems (DG-056) and Transient Non-Community (TN) Water System Resources. Testing frequency and requirements vary depending on the type of system and a variety of other factors. The DNR sends monitoring schedules to public water system owners and operators every year indicating what types of monitoring must be done and when. Required reporting forms can also be found in this packet. You can download additional copies of needed forms at laboratory analysis forms. Make sure you submit samples on time to remain in compliance!

All samples must be submitted to a laboratory certified for doing safe drinking water analysis along with proper lab slips. Lists of certified laboratories are available at laboratory testing. The laboratory will provide the sample results to you and will submit the results electronically to the DNR. If the results exceed an MCL, DNR will notify you and will provide guidance on next steps. At transient non-community systems in many counties, a certified sanitarian from your Public Health Department will collect your water samples for you.

If a contaminant is detected in a sample, you will have immediate retesting requirements. If contaminants are confirmed in the water supply, you will have to take action to provide safe water.

Be sure to keep copies of all sampling results for your records.

How do I deal with contaminants?

If your water system exceeds a Maximum Contaminant Level (MCL), you will first be required to retest the water to verify the contamination. If retesting confirms contamination, you will be required to take immediate action to provide safe water. See the table of MCLs and work with DNR staff to investigate drinking water problems and get back into compliance.

If contaminants are found, you may be required to notify the public of the contamination and the precautions that are necessary to obtain safe drinking water. You also must submit a copy of the notice to the DNR along with a signed certification of public notice.

In some cases, treatment may be necessary to provide safe drinking water. DNR approval may also be required to install a water treatment device, such as a water softener or reverse osmosis system. If a treatment device is installed, you will also be required to conduct increased monitoring to ensure it is functioning properly.

Do I have to provide a consumer confidence report?

Community (municipal and non-municipal) water systems are required to provide a Consumer Confidence Report (CCR) to all customers on a yearly basis. Key components of the report include a summary of the water testing conducted during the year and the results, as well as potential health effects of any violations and methods used to remedy the problem. The report must be distributed to your customers by July 1 for the previous year. A copy of the report should also be sent to your district DNR field representative along with a signed certification form.

DNR has an optional online CCR generator to help you create your report which can be customized to fit your individual requirements. For more information on generating a report, see instructions for creating and customizing a consumer confidence report using DNR's CCR generator.

Will my public water system be inspected?

All public water systems receive inspections (sanitary surveys) on a regular basis which are conducted by the DNR or contracted county health department staff. Typically, an inspector will call ahead to schedule an appointment. Sanitary surveys evaluate the adequacy of the water source and examine the facilities, equipment, operation, maintenance, monitoring, record keeping and any required public noticing. Community systems will receive a sanitary survey once every three years and non-community systems will receive one every five years. After the inspection, you will receive a report which will outline corrective actions if any are needed.

The sanitary survey is an opportunity to discuss your water system with your inspector, ask questions and catch potential problems with your water system before they lead to unsafe drinking water. Be sure to keep copies of your inspection reports for future reference.

You will want to prepare your records before you are inspected. You can also contact the Wisconsin Rural Water Association or DNR staff prior to an inspection for technical assistance that will help you get ready.

I am on a municipal water system. Will I still get inspected?

Businesses using a municipal water system will sometimes be inspected by the municipality. Municipalities often inspect to ensure piping is not allowing contamination to flow back into the potable water supply, known as backflow. The U.S. Environmental Protection Agency (USEPA) defines cross-connection as "any actual or potential connection between the public water supply and a source of contamination or pollution". You will know you have a cross-connection if you have any physical connections between your plumbing system and the municipal water supply. If this is the case, you must ensure there is no backflow by installing a backflow prevention device to prevent contamination. For more information about preventing backflow, see USEPA's Cross-Connection Control: A Best Practices Guide or Information about Public Water Systems.

What if I have a high capacity well or multiple wells?

If your public water system will have a pump capacity of 70 gallons per minute or more, it is considered a high capacity well system and additional approvals will be needed prior to beginning construction. If you operate a high-capacity system, all wells on the property are considered high capacity regardless of size and approvals are written for all wells on the property together. High capacity well rules also apply to all school wells and wells at wastewater treatment plants regardless of capacity.

A high capacity well application and fee are required and must be approved by the DNR before you begin construction, reconstruction, or operation of a high capacity well system or before the system recommences operation following a change of ownership. Well construction requirements also differ from those for lower capacity wells.

Once your application is submitted, DNR staff will review it to see if the wells on your property will have a significant adverse impact on waters of the state which will determine whether or not the application is approved. Once approval is granted, well owners are required to report their annual withdrawal amounts to the DNR. Reporting water use will tell you how to report. Additional requirements exist if your system is within the Great Lakes Basin. See water use permitting for details on obtaining a water use permit for withdrawals from the Great Lakes Basin.

More information can be found at high capacity well information.

What is required for property transfers?

Water system inspections are sometimes conducted during a property transaction. Inspections are not required; however, if an inspection is conducted, it must be by a licensed well driller or pump installer. The DNR has a list of licensed well drillers and pump installers. Property owners are required to identify and properly fill and seal any unused or non-compliant wells on their property. See property transfer inspections if this applies to you. You can also look up information on water quality for a given property on the public water supply system data search page.

If ownership of a high capacity well system changes, submit the High Capacity Well & Surface Water Withdrawal System Ownership Change (3300-266) form. A high capacity well application and fee are required and must be approved by the DNR before the system recommences operation following a change in ownership. When property containing lower capacity wells changes ownership, the DNR must also be notified of the change.

Who do I contact for assistance?

The Small Business Environmental Assistance Program at the DNR offers advice to small business owners on environmental requirements. You can contact a Small Business Environmental Assistance Specialist through the Small Business Hotline 855-889-3021 or email your questions to Additional information and resources are available on the Small Business Environmental Assistance Program website. Go to the DNR and search "small business".

DNR Drinking Water & Groundwater Staff Contacts offer one-on-one technical assistance to help you understand the regulations.

The DNR also has a contract with the Wisconsin Rural Water Association (WRWA) to provide technical assistance to other-than-municipal (OTM) and non-transient non-community (NN) systems. These systems can receive one-on-one assistance on drinking water issues from WRWA.

Additional resources