SIOUX FALLS, S.D. (KELO) – When hot summer days arrive, more water usage follows. 

That keeps Darin Freese and a team of roughly 30 people at the Sioux Falls Water Purification Plant busy. Built-in the 1950s and expanded in the 1970s, the plant operates 24/7, 365-days a year to make sure when you turn on a faucet, you get treated quality water pouring out.    

Freese, who has worked at the city water plant for more than 20 years, is the water program coordinator for the city of Sioux Falls. He’s a champion of water conservation and praises the city’s lawn watering ordinance that has homes watering on odd/even days that match the house number. The policy also prohibits noon to 5 p.m. watering each day.  

“We’re doing well. We’re keeping up with demands,” Freese told KELOLAND News. “People are following the watering schedule very well. Complaints are down.” 

Standing in front of a water filter that can process 5 million gallons a day, Freese explained how the lawn water schedule has been a big boost to the water plant. Instead of possibly having 60,000 water services running all at the same time, the plant sees half that amount.  

“If we’re making 42 or 44 million (gallons per day) and if everybody was using, you could double that usage,” Freese said. “We just couldn’t handle it. We don’t have the capacity.” 

Freese said when the plant isn’t running at its highest capacity, it saves on the infrastructure, aiding pipes and lessening the need for more water towers, reservoirs and storage. The plant has 15 water filter tanks that can each roughly filter 5 million gallons a day for a maximum capacity of around 75 million gallons a day. 

“We’re shaping peaks, peak flows and peak electrical demands,” Freese said. “We save money on electricity when we’re not running those expensive pumps because everybody is using water.” 

Irrigation experts, according to Freese, believe watering deeper every two or three days is more beneficial for grass yards than watering every single day. 

Where does the water come from? 

The city pulls water from three main sources – wells in the Big Sioux aquifer, the Lewis and Clark Regional Water System, which pulls water from the Missouri River, and the Big Sioux River. 

Freese said the city’s max contract allocation from Lewis and Clark is 17 million gallons a day, which falls to around 9 to 10 million gallons a day in the winter. For comparison, one million gallons of water is equal to a swimming pool nearly as long as a football field, 50 feet wide and 10 feet deep. 

He said currently the plant is taking about 15% of its water from the Big Sioux River, but it can make up as high as 50% of the water. 

“The rest of the difference is all made up with wells coming out of the Big Sioux aquifer,” Freese said. 

As Sioux Falls continues to see rapid growth, Freese said the water plant and public works department plans in terms of 10 and 20 years ahead. While he said you could assume each person in Sioux Falls uses around 40 to 45 gallons of water per day, he believes water conservation practices have helped people be more aware of water usage and shortages. 

“We’re designing pipe capacity, infrastructure decades ahead,” Freese said. “When people come to town, they gotta know the water is there. We have to stay out ahead of it and we do feel we do a very good job of it.” 

The water plant is only as good as the water sources it can draw from. Freese mentioned more water sources could come from the Lewis and Clark system as it expands capacity, but also the Big Sioux River and Big Sioux River aquifer wells. 

“We have started to place really high efficiency, big volume wells in the best places of the aquifer,” Freese said. “We’re putting in the wells now but that research was done decades ago because that’s where we have to be. We got to be out in front of it.” 

How much water are we using? 

The amount of water people use each day varies a lot from season to season. In the winter, the water plant will see around 16 million gallons a day be used. That amount climbs to around 42 million in the summer months, an increase of 26 million gallons a day. 

Last year, Freese said the city’s water plant had a peak of 46 million gallons in a single day. He said so far this summer, the city has reached 44 million gallons in a single day. 

“It’s very busy for us on Thursdays and Fridays because people water before they go out of town,” Freese said. “We take pride in making sure that everything runs smoothly.” 

Freese said the most challenging part of the water plant can be preparing for water usage increases but then clouds and rain appear. 

“The increases are much less difficult than the decreases,” Freese said. “The treatment process likes consistency. It’s to our advantage to make sure that we stay on top of it and make lots of small changes versus one big change”

When the Big Sioux River’s flow is at 50 cubic feet per second or less for 10 consecutive days and city demand is more than 42 million gallons per day, the city moves to stage 2 lawn watering restrictions. Stage 2 water restrictions only allow businesses and homes to water lawns one day per week.   

“Last year, we were two times, one day away from going to stage two restrictions but then we got some timely rains,” Freese said. 

Like last year’s drought, Freese said the Big Sioux River was down early in the spring, but timely rains have added water to the river and helped the well field as well.  

What about all those car washes? 

In Sioux Falls, you don’t have to look far to find a car wash

Sioux Falls is home to a lot of car washes and their water usage is factored in for both winter and summer water demands, Freese noted. Freese added the state and city don’t have a required recycling amount of water for car washes, but he noted when plans are submitted they have extensive water recycling capacities.

“They recycle a vast majority,” Freese said. “When your main product that you use to make money is a precious, expensive resource there’s incentive there for them to recycle.” 

The average amount of water used at a self-serve car wash is 17-18 gallons, according to the Western Car Wash Association. An International Carwash Association study found car washes used recycled water at as high as 82% and a low of 9%.