Best Practices

While this page includes steps specific to certain pollutants, your facility can take general best practices to minimize pollution and waste, potentially reducing costs as well as protecting water.

  • Conduct preventative maintenance to ensure proper function of valves, pretreatment equipment, and other machinery keeping waste out of the sewer.
  • Train employees on what can and cannot go down the drain. 
  • Control inventory to avoid wasting surplus materials.
  • Conserve water in your facility, which can reduce the mass of pollutants discharged in some cases.
  • Substitute hazardous process chemicals, cleaners and other materials with less harmful alternatives. (OSHA toolkit for substitution and alternative to hazardous chemicals)

Pollution Prevention for Industries

Industries often use a large amount of water and chemicals in their manufacturing processes. Some industries use or produce highly specialized and potentially hazardous substances by their nature, such as pharmaceutical producers. Accordingly, there are industry-specific recommendations and requirements to minimize pollutants going to the sewer system.

MMSD also issues permits to specific types of industries as part of its Pretreatment Program. Whether your facility has a permit or not, the following actions can help minimize pollution at your facility and protect water quality. 

General Industry Pollution Prevention

  • Planning a new discharge to the sewer? Complete an industrial request to discharge form (IRDF) and return it to MMSD at least 60 days prior to the expected date of the new discharge. MMSD’s Pretreatment Coordinator will review the form and determine whether the discharge to the sewer system is allowable.
  • Review MMSD’s Sewer Use Ordinance to understand which wastes can and cannot go down the drain, as well as allowable amounts of various pollutants. Chapters 5, 6 and 7 are particularly relevant to industrial facilities. Section 5.2.3 includes specific limits for various pollutants that apply to all industrial users, permitted or not.
  • When in doubt, contact MMSD about the safety or appropriateness of a given chemical to be disposed of down the drain.


  • Conduct a mercury inventory of your facility to determine if mercury devices or materials are still in use or in storage. (Example inventory)
  • Replace mercury-containing materials with mercury-free alternatives. Wisconsin DNR has a partial list of alternatives on its mercury overview webpage
  • Label any remaining mercury-containing materials, such as boiler switches, to help ensure they are properly disposed of when replaced.
  • Keep mercury spill kits on hand if your facility has historically used or contained mercury products. If there is a mercury spill in your facility, follow proper clean-up procedures -- never dispose of mercury down the drain or in the trash.
  • Train employees on proper mercury clean-up procedures.
  • Verify the purity of process chemicals with your supplier. Some chemicals, such as caustic soda, bleach and ferric chloride, can contain trace mercury if produced by a certain process.
  • Handle old plumbing fixtures, such as sumps and traps, as potentially mercury-containing waste when conducting renovations or demolitions. Mercury can settle in these fixtures, making them hazardous waste.


  • Reduce salt use in your water softeners to minimize salt discharges to the sewer system. MMSD is providing grants for projects that permanently reduce chloride to the sewer system. Example salt reduction projects, as well as case studies of facilities that have successfully reduced salt, are available on our Salt Reduction Resources page.
  • Enact a winter maintenance policy for company grounds that incorporates best management practices for road salt application to parking lots, driveways and sidewalks. Recommended practices are found at