Phillip H. Tollefson Water Treatment Plant

Facility information

Built in 1942, the Phillip H. Tollefson Water Treatment Plant is our original water treatment plant and primarily treats water from local sources.

It was originally built with a capacity of 6 million gallons per day (MGD), but we’ve expanded the plant’s capacity four times since then. We now have the capacity to treat up to 42 million gallons of water daily.

Recent upgrades include a state-of-the-art pretreatment building, a new raw water vault, and indoor basins for better environmental control. Planning for additional improvements is underway.

Aerial photo of Tollefson water treatment plant. Two large brick buildings, parking lots, cars, a white water tower, & 2 ponds make up the footprint.

Facility tours

Our facility tours are a great way to learn about the water treatment process and all of the physical, chemical and biological changes that transform raw water into safe drinking water.

Tours are tailored to fit the specific needs of a school or organization and are available to our customers at no charge.

  • Age requirement: 5th grade or 10 years old & up
  • Group size: Five attendees minimum*, 20 maximum
  • Tour length: 60 minutes
  • Days offered: Tuesday-Friday
  • Start time: Mornings between 9-10 a.m. and afternoons between 1-2 p.m.
Groups of five or more can request the date and time of their choice for available days.
Register for this tour
Read our full tour policy

Public tour dates

*For groups smaller than five, please register for one of our regularly scheduled public tour dates:

  • Tuesday, July 21, 2026 at 9 a.m.
  • Tuesday, Nov. 17, 2026 at 1 p.m.

Appropriate dress, which includes long pants (no dresses or skirts), closed-toed walking shoes, and clothing/accessories for expected weather, is mandatory for all tours. Due to safety concerns, visitors with inappropriate dress will not be able to tour the entire operational facility. We provide additional safety equipment, when required, to tour a facility (i.e. hard hats, safety glasses, ear protection).

Tours are scheduled in the order requests are received. Tours must be requested at least three weeks in advance.

Tour registration form