Please ensure Javascript is enabled for purposes of website accessibility

The Denmark Wastewater Treatment Plant

The Village constructed its new advanced secondary wastewater treatment plant in 1979-1980 and it became operational in September 1980. The plant was designed for an average daily flow of 600,000 gallons per day and a BOD of 1,665 pounds per day. This treatment facility (located at 400 Mahlik Lane) was expanded in 1992 to further increase the BOD capacity to 2,665 pounds per day with the addition of a biological filter ahead of the existing rotating biological contactor (RBC) process.

The wastewater generated within the Village travels through approximately fifteen (15) miles of sanitary sewer to a pump station located adjacent to Denmark Creek. Three (3) raw sewage pumps lift the wastewater to the head of the plant for treatment.

The treatment facilities include preliminary treatment with a fine screen and grit removal. Primary treatment consists of a forty (40) foot diameter primary clarifier where both scum and sludge are removed from the wastewater and treated in two (2) anaerobic digesters. After treatment in the primary clarifier, the wastewater is biologically treated through a fifty (50) foot diameter trickling filter followed by a four (4) stage rotating biological contactor process (RBC's). Phosphorus removal is achieved through chemical precipitation using Ferric Sulfate. After the RBC's the wastewater flows through two (2) final clarifiers in which the biological solids produced in the RBC process are removed and either recirculated to the primary clarifier or thickened by a a gravity belt thickener prior to anaerobic digestion and land application. Following the final clarifiers the treated wastewater is aerated through step aeration prior to discharge into the Denmark Creek, which is a tributary to the Neshota River.

The Denmark Wastewater treatment Plant has septage receiving facilities in which only septic and holding tank waste is accepted. Licensed waste haulers are required to secure a permit from the Village authorizing discharge.

Chlorides and Water Softeners

The Wisconsin DNR is proposing new chloride discharge limits for the Village's wastewater discharge permit in 2017. Chlorides are something that cannot be treated at the wastewater plant; therefore, we must concentrate on reducing chlorides at their source

One of the main factors that influence the amount of chlorides in the water coming to the treatment plant is water softeners.

Check your Water Softener
Ensure Optimal Performance of your Water Softener Unit

  • Look to see how it is calibrated. Some softeners are preset at the factory at 30 grains, the highest hardness setting. Reset the hardness to 24 grains.
  • Consider updating your old softener with a high efficiency demand based unit which offers a number of environmentally friendly benefits. These include lower water and energy use and decreased salt needs.
  • Soften everything except the kitchen cold and outside faucets. Hard water tastes better and softened water is unnecessary for outside faucets.
  • Check the timer. You may be able to increase the amount of time between regeneration cycles without affecting water quality. Experiment by increasing the interval by one day at a time and monitor the effect on dishwashing and laundry. If hard water is coming through at the end of the cycle, you will find you need to use more soap to obtain the desired amount of suds. When you determine the time frame when hardness is coming through, set your timer back one day.

By keeping your equipment in good operating condition and properly set, you can help the village meet the limits of our upcoming DNR permit , keep sewer rates low, and help maintain the quality of our lakes and rivers.

Information on water softeners

The Department of Natural Resources recognizes the impact that salt has on the environment and recommends the adoption of a chloride reduction ordinance. The Village of Denmark has adopted an ordinance requiring the installation of on demand water softeners with an effective date of October 2019. On demand only function as needed rather than running on a predetermined schedule, significantly reducing the amount of chlorides which, cannot be treated in a cost effect manner, from entering the environment. Please help the Village in this effort to improve the quality of life for everyone.

  • 238-2831 Water softener discharge
    [Added 10-14-2019 by Ord. No. 2019-04]

Chloride reduction. As recommended by the Wisconsin Department of Natural Resources and in order to reduce chloride in wastewater treated in the wastewater treatment facility, the following rule is created with regard to water softener installation.

    1. Chloride reduction.  As recommended by the Wisconsin Department of Natural Resources and in order to reduce chloride in wastewater treated in the wastewater treatment facility, the following rule is created with regard to water softener installation. Water softeners.
      (1)  All new or replacement water softeners installed in residential, commercial, industrial and institutional buildings within the Village limits and served by the Village wastewater treatment facility shall be "demand based" water softeners, Water softeners functioning only at predetermined time intervals shall no longer be permitted in the Village.

(2)  The provisions of Subsection (A)(1) shall become effective the first day of October, 2019.


Current rates are:
$9.84/1,000 gallons holding tank waste
$65.56/1,000 gallons septic tank waste

Water Utility Fees:
2022 Water Rate Sheet

DNR - Mark Stanek
Any questions concerning your bill should be directed to Sherri Konkol at 863-6400 or [email protected]