How DeKalb Gets Its Drinking Water

Nov 4, 2019

Ensuring safe drinking water is a complex process.

For modern water sources, there are two general options. The first is for a community to draw from a large surface source, such as a river or lake. But that’s not an option for DeKalb.

“In the summer times, sometimes there’s not even enough water flowing in the Kishwaukee River, so [it's] not really a reliable source of water for DeKalb," said Bryan Faivre, the director of utilities and transportation.

A pipe carrying well water from inside the Dresser Road Treatment Plant.
Credit Chase Cavanaugh

He says DeKalb makes use of nine wells spread across two different aquifers. Six of them are quite deep.

“The Sears Tower is about 1200 feet tall. So if you were to imagine how tall that tower is, that’s how far we drill into the ground to get our water supply," he said.

Fortunately, supplies are abundant, so the pump only needs to go about 400 feet below ground. Other wells are shallow, but both water supplies require a different form of treatment. The deep well water needs to be softened to filter out radium deposits.

Interior view of the treatment plant. Water softening occurs in the pipes on the left. Iron is filtered from the water in the tank on the right.
Credit Chase Cavanaugh

“DeKalb’s level, the raw water is about at 7, and the maximum contaminant level is 5 for radium," Faivre said.

To do this, the treatment plants run the water through a resin made from a salty brine.

“As the water passes through, the magnesium, calcium, radium attaches to the resin and are replaced by the sodium ions," he said.

Some DeKalb homes still have water softeners of their own, but the city’s five treatment plants take care of that process now. Shallower wells don’t have issues with radium, but their water has high levels of iron.  To reduce the mineral buildup, Faivre says the plants prepare the water for filtration. 

“What we do is blow air into the water, which then precipitates iron out of the water," he said. "We want that water to turn rusty-color.”

That water is then run through a large tank full of sand, which filters out the iron. Even though the city’s five treatment plants take water from different wells, the water is both softened and filtered to ensure a consistent product.

Hoses connected to tanks add chemicals to the softened and filtered water. The lowermost hose no longer adds caustic soda (NaOH) to the water supply. It was previously used to adjust water pH.
Credit Chase Cavanaugh

Finally, before being piped out to DeKalb, the water receives three types of chemicals. One is fluoride, for dental health.

Another is chlorine, to remove germs.  Faivre says this is a problem in stagnant water. 

“The water itself is pretty pure coming out of the ground, but once it leaves the treatment plant out into our distribution system, it may sit there for a period of time, so we need a disinfectant that will remain in the water," he said.

Finally, there’s phosphate, which acts as a protective coating to stop any building-based plumbing from leaching lead into the water.

Tanks of chlorine are kept in a separate room before their contents are added to the outgoing water supply.
Credit Chase Cavanaugh

“From here, once the water leaves the treatment plant, it can either go into our water tower or it can go out into residents’ homes or businesses. It kind of flows wherever it’s needed, more or less," he said.

Faivre says the water towers are essential for getting the water to flow through the pipes.

“We’re getting our pressure by elevating our water up to a certain level, 120, 130 feet up in the air, and then it’s just gravity-fed back into the system," he said.

Every night, the city pumps water into the towers, and it’s drawn from them as needed. And there’s little risk of running out.

“Our four water towers. We can store 5.7 million gallons in storage. We use about 3 million gallons a day," Faivre said.

Treatment plants like Dresser make use of labs like these to test water quality.
Credit Chase Cavanaugh

The rest is kept as a reserve for heavy demand, such as fighting a fire.  The only exception to this is what Faivre calls unaccounted water loss.  He says a lot of water was lost this way in the 1980s.

"30% of the water that would be leaving our treatment plant or our production side, we really had no idea where that water was going," he said.  "Many communities were that way because back then it was cheaper to produce water than it was to monitor and conserve the water by reducing unaccounted water loss."

Fortunately, fixing water main breaks and malfunctioning meters has brought that level down to approximately 5%. The plants also run regular water tests to keep an eye on contaminant levels.