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ECAR Fact Sheet for Wisconsin
Floor Drains

Self-Audit Checklist
Best Management Practices
Related ECAR Fact Sheets
Other Relevant Resources


The following fact sheet was prepared by the ECAR Center staff. Once prepared, each ECAR Center fact sheet undergoes a review process with the applicable state environmental agency(ies). You can check on the status of the review process here. Please read the disclaimer on the status page. While we have tried to present a summary of the essential information on this topic, you should be aware that other items, such as local regulations, may apply to you.

What You Need to Know

Floor drains, especially those built when designers and contractors were much less environmentally conscious than they are now, can be full of surprises.  If you do not know what is happening at the other end of yours, you would be well advised to find out before an inspector does.

Floor drains in many industrial facilities have been found to empty into surface waters, or into septic fields.  In either case, the discharge of wastewater from the shop floor into this kind of system may be illegal.  If the floor drain discharges into a city sewer system, it will need a permit, and will need to be periodically monitored.  Floor drains can also leak, and have been known to cause serious and costly soil and groundwater contamination problems.  This fact sheet will help you determine if the floor drains in your facility are properly connected and properly used.


This fact sheet addresses regulatory issues and practices associated with floor drain systems. A floor drain system commonly includes a concrete trench, which runs down the center of a shop floor that may lead to underground pipes and/or tanks. Instead of a trench, some shops have single or multiple rectangular or round floor drains. Typically, the shops floor is slightly sloped to allow liquids to flow into the floor drain.

A floor drain is a red flag for any inspector from an environmental protection agency. Their concerns are primarily:

  • What types of materials could potentially enter the floor drain system, and
  • What ultimately happens to those materials?

It is very important to know where all your floor drains lead, and are aware of the Wisconsin Department of Natural Resources (DNR) regulations that apply to your discharge activities. If you do not know where your drains lead, or if you using floor drains improperly, you could be contaminating nearby surface waters or drinking waters.

Some floor drains lead into a sanitary sewer, where wastewater goes directly to a sewer system or treatment plant. Sometimes floor drains lead directly to an underground holding tank or discharge to a waterway or to the ground outside. DNR's water pollution control regulations apply to all of these activities.

If you want to discharge industrial wastewater to waters of the state, you must have a Wisconsin Pollutant Discharge Elimination System (WPDES) permit from DNR. Examples of waters of the state include streams, rivers, lakes, ponds, marshes, waterways, wells and springs. If your floor drains lead to any water of the state, you must have a discharge permit for this activity.

Companies that discharge industrial wastewater directly to a sewer system or treatment plant are also regulated. Check with your local sewer authority or treatment plant to determine whether you need a permit. In addition, you may be required to treat the wastewater before discharging (e.g. oil/water separation, removing solids, chemicals, etc.).

Links to the Regulations and Forms. Use the following links to view the regulations and permit forms pertaining to floor drains.

WPDES General Permit Notice of Intent Form

WPDES General Permit Information

Federal Rules for Class V Wells

Federal Rules for Motor Vehicle Waste Disposal Wells

Self-Audit Checklist

When an inspector comes to your facility, there are certain things he or she checks to see if you are in compliance with environmental regulations. It makes good sense for you to perform a "self-audit" and catch and correct problems before they result in penalties. Also, there are some compliance incentives associated with self-audits (see Audit Policy Page).

Use the following list to audit your floor drain system.

  1. Do your floor drains discharge to the ground, a water body or storm sewer? Are the discharges authorized by a permit? If you are using floor drains to discharge industrial wastewater to a water body you must have a Wisconsin Pollutant Discharge Elimination System (WPDES) Permit. This includes discharges into storm sewers. In some areas of the state, such as those over sole source aquifers, discharge to ground may not be allowed or may require further controls.
  2. Do your floor drains discharge to a city sewer system? Are the discharges authorized by a permit? If you are using floor drains to discharge wastewater to a local wastewater treatment plant, make sure the treatment plant knows about this activity. You may be required to conduct pretreatment on the wastewater before discharging it. You also may need to get a permit or written notification for the discharge.
  3. Is oil or solvent discharged to floor drains? These are RCRA regulated wastes and must be removed and properly disposed of. If the floor drain system is connected to the city sewer system, Federal and state laws prohibit the discharge of oil or flammable solvents.
  4. Is your floor drain connected to a septic tank or dry well? If so, you may be violation of state law. You must be registered with DNR to operate a septic tank, and it must be closed within 1 to 3 years.

Best Management Practices (BMPs)

Most regulations tell you what you have to do to be in compliance, but they don't explain how to do it. That's where "best management practices" come into play. BMPs are proven methods that help you to get into compliance and stay there. The following BMPs are recommended for floor drains.

  • Check all of your floor drains and make sure you know where they drain.
  • Cap or plug floor drains that are not serving a useful and lawful purpose.
  • Use drip pans or similar devices to collect vehicle fluids before they reach the floor drain system.
  • Do not put fluids like oil, solvents, paints or chemicals into a floor drain.
  • Install berms in the shop around areas where chemicals are stored to prevent their entry into the floor drain system.
  • Install screens in drains to prevent solids from entering the floor drain system.
  • Develop and implement a maintenance schedule for inspecting and cleaning the floor drain system.
  • Prepare and train for emergencies. Have a plan in place to quickly cleanup a spill before it escapes.
  • Use dry cleaning methods such as sweeping instead of water cleanup, whenever possible.
  • Don't hose down your work area. This practice generates large quantities of contaminated wash water.
  • Consider sealing your shop floor with epoxy or other suitable sealant.


  1. For more information, contact Wisconsin's DNR Auto Salvage Sector Resource Specialist at 715-831-3263, or contact the WDNR Regional Office in your area. For northern Wisconsin, call 715-635-2101 or 715-365-8900; West Central Wisconsin, call 715-839-3700; Northeast Wisconsin, call 920-492-5800; Southeast Wisconsin, call 414-263-8500; and, for South Central Wisconsin, call 608-275-3266.

  2. All spills should be immediately reported using Wisconsin's 24-hour toll free hotline at 800-943-0003. If you discover a discharge through analysis of soil or water, use the Hazardous Substance Release Fax Notification Form.

Related ECAR Fact Sheets

  1. Wastewater
  2. Septic Tanks and Disposal Wells
  3. Stormwater

Other Relevant Resources

  1. Managing Floor Drains and Flammable Traps, Minnesota Pollution Control Agency Document


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