What happens to your water once it goes down the drain?

Watertown Utilities Superintendent Doug Kammerer uses a long rod to measure the depth of the sludge at the bottom of a clarifier at the wastewater treatment facility. The clarifier is one of several steps involved in filtering wastewater before it is dumped into the Crow River. (Staff photo by Matt Bunke)
Watertown Utilities Superintendent Doug Kammerer uses a long rod to measure the depth of the sludge at the bottom of a clarifier at the wastewater treatment facility. The clarifier is one of several steps involved in filtering wastewater before it is dumped into the Crow River. (Staff photo by Matt Bunke)

If you’re anything like most people, you probably don’t give much thought to what happens to the water once it goes down the drain in your shower, sink or toilet.

Doug Kammerer was like that once. Of course, that was long before he became the Utilities Superintendent for the City of Watertown.

“Many years ago, before I got into the field, I flushed the toilet and I didn’t care,” Kammerer said of a common attitude that can often lead to clogs in the city’s complex sanitary sewer system from people flushing unflushable items down the toilet. “I thought, hey, out of sight, out of mind. As long as it doesn’t back up, I’m good.”

But what Kammerer didn’t think twice about back in his younger days now makes up about 90 percent of his job. What most people find gross, Kammerer finds fascinating.

“I enjoy every second of it,” Kammerer said. “I like seeing how dirty that water is when it comes in, and how clean it is when it goes out. It kind of gives you a sense of pride.”

Part of Kammerer’s job is to address clogs in the system, whether that’s in the sewer system, in one of several lift stations throughout the town, or at the actual wastewater treatment plant. Those clogs can be caused by anything as simple as paper towels or towelettes — which usually aren’t nearly as biodegradable as advertised — to things far more baffling. In the past, Kammerer has pulled everything from boys’ underwear to T-shirts to PVC piping out of the sanitary sewer.

The bulk of Kammerer’s job, though, is to make sure the complex system, and in particular, the wastewater treatment plant, keeps running smoothly at all times. That’s in large part because the big-picture answer to the question, “Where does the water go once it’s down my drain?” might surprise you.

In a way, that wastewater is basically recycled. Once it’s cleaned and filtered at the wastewater treatment plant in Watertown, it’s dumped into the south fork of the Crow River, which flows into the Crow River, which flows into the Mississippi River. Numerous larger cities — including Minneapolis — take their water directly from the Mississippi River, meaning the water you flush down your toilet in Watertown could one day end up coming out of a faucet in Minneapolis.

Pretty gross, right?

At first, maybe. But once you understand the full process of cleaning that wastewater, it’s far more fascinating than it is disgusting. The murky gray water that first flows into the plant is transformed into water so clear by the time it leaves that you can see the bottom of the nine-foot basin that it sits in before being pumped into the river.

“This facility has been so good that when people come out here from St. Cloud Technical College, or even from the (Minnesota Pollution Control Agency), they can’t believe you can see the bottom of the tank,” Kammerer said. “It’s 9 feet down, and you can see the bottom of the tank. You can’t even do that in some lakes. It’s very clean, and that’s what we’re putting in the river.”


A long journey

Once the water flows through the drain in your home, it flows out to the city’s main line, which varies from 10 to 40 feet beneath the surface. There’s no big secret in getting the water to the treatment facility — it’s just gravity that does the work.

The water starts at 10 feet beneath the surface, and gradually flows downhill through the nearly 24 miles of sanitary sewer lines that the city of Watertown maintains. Once the water reaches a depth of 40 feet beneath the surface, it flows into one of seven lift stations in the city. There, the water is elevated back to the original 10-foot depth, where it begins its downward descent all over again.

Some wastewater needs only to travel a few blocks to reach the wastewater treatment facility, which is located at the City’s Public Works facility on County Road 27 just north of town. Other wastewater, though, such as the water from the Wildflower development, must travel through two lift stations during a four- or five-hour journey.

When it arrives at the wastewater treatment plant, the wastewater is first filtered by a bar screen, which is basically a metal rack with 1/2 inch spacing between each bar. The screen is designed to remove larger debris such as paper towels, sticks, or other items, but some items do make their way though. They eventually end up clogging several pumps later in the system.

“Newer technology called micro screens will take everything out, because its a smaller opening that’s only allowing water to get through,” Kammerer said. “But the thing I’m trying to get across to people is you shouldn’t be flushing this stuff anyway.”

After flowing through the bar screen, the water makes its way into one of three aeration basins, each of which holds 130,000 gallons. Each basin is 65 feet long, 17 feet wide and 16 feet deep.

It’s here, Kammerer said, that the true action takes place. Microscopic parasites, or “bugs,” as Kammerer calls them, feed on the solids in the wastewater, removing some of them before the liquid moves through to the next step. The “bugs” occur naturally in the wastewater, but must be monitored closely to make sure there are always enough of the “good bugs” and not too many of the “bad bugs.”

“I look at the bugs a lot under the microscope, and that will tell me how the plant is doing,” Kammerer said.

After flowing through the initial aeration basins — with some of the solids being removed by the “bugs” — the water then flows into two large domes, where the water sits for a period of time in settling tanks known as clarifiers. Each tank is 34 feet in diameter and 14 feet deep, and is designed to let the solids sink to the bottom. The now even-clearer water at the top is then filtered into the next stage of the cleaning process, while some of the of the sludge that gathers at the bottom at is either pumped into storage — where it eventually is transported away to be used as fertilizer on farmers’ fields — or is pumped back to Step 1, where it begins the cleaning process all over again.

The liquid water that is filtered out of the clarifiers is then pumped into another building, which houses what is known as a traveling bridge filter. This system basically uses 8 to 10 inches of sand to further filter the water, and after the sand becomes too clogged for the water to flow through, a traveling bridge goes back and forth to clean the sand.

Kammerer said the traveling bridge filter that was built at Watertown’s facility, which opened in 1994, was one of the first in the state.

“Way back when they decided to build this facility in 1992, there were pretty stringent rules the MPCA put on Watertown to dump in the south fork of the Crow,” Kammerer said. “They had to add something to take out some solids, and this was one of the first three in the state.”

After the sand filtration process, the water is pumped into one final basin, called the chlorine contact basin, for disinfection. Chlorine gas is fed into the wastewater as it enters the basin, which ensures the destruction of pathogenic bacteria, including some of those “bugs” that help clean the water in the early stages of the filtration. The water takes about 20 to 25 minutes to flow through this process, before it is fed with sulfur dioxide to remove the excess chlorine and make sure the water has adequate oxygen for aquatic life before it is fed into the river.


How clean is it?

The cleanness of wastewater is measured by BOD, or Biochemical Oxygen Demand, which is measured in terms of milligrams of oxygen consumed by organisms per liter. Prior to the construction of Watertown’s wastewater treatment plant, the pond system the city used for filtering the water resulted in a typical BOD of about 30.

When the MPCA changed regulations in 1991 to require a BOD of 5 or lower, Watertown was forced to change from its pond system to the current mechanical system. Today, Kammerer said the facility has been averaging a BOD of about 2.5.

“We went from a 30 to a 2.5, which is tremendously helping out the river,” Kammerer said.

Kammerer said the idea that he’s making a difference as far as natural resources are concerned is one of the major appeals of the job, especially since he’s a hunter and a fisherman. But despite the fact that his father was a street superintendent for 30 years, Kammerer didn’t always know he’d end up in this line of work.

In fact, Kammerer said he spent 10 to 12 years working in retail before deciding to pursue this line of work.

“(My dad) kept telling me, Doug, you should go into water and wastewater,” Kammerer recalled. “Well, I was in retail for 10 to 12 years and I was working a lot of hours, and I started to think maybe I should look into it. The more I looked into it, the more interesting it got.”

Kammerer went back to school at St. Cloud Technical College for about a year, and then it took him about another year before he landed his first job in Watertown.

“When I first started working here, I was as green as could be,” Kammerer said. “I walked down into that basement and saw all those pumps, and thought ‘What am I getting myself into?’ The best thing I ever did was grab the plans of the facility and go home at night — and this sounds really dorky — but I’d go home and roll them out and look at them. All of a sudden, this seemed like a piece of cake.”

Watertown is fortunate to have an operator like Kammerer, who has an A Wastewater license, which is one step higher than Watertown’s Class B Wastewater facility. Not every city is fortunate enough to have that, as evidenced by the city of Watertown’s agreements with the cities of Cologne and Norwood Young America. Those cities don’t have licensed operators, so Kammerer spends several hours a week at each of those facilities as well.

“It’s interesting, to say the least,” Kammerer said of his job. “It’s something different every day. It’s not easy, and you have your good days and your bad days, just like everybody else does. But it’s very interesting.”


Contact Matt Bunke at [email protected]

  • Bratista

    This is really fascinating! What about septic systems? What happens there?

  • Jim Rousey

    So for every gallon of water flushed through the toilet, what volume or percentage of a gallon of water is returned to the river by the end of the process?