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Cedar Rapids’ water treatment process begins before the water ever enters our plants. We use a multi-barrier approach to protect our drinking water and ensure high quality. We carefully monitor the water throughout our system starting with an ongoing watershed and wellhead protection program through the water treatment processes and into the distribution system – right up to your tap.



1. Aeration
Once the water has been drawn from the wells into the City’s treatment plants, it undergoes aeration. Raw or untreated water is allowed to cascade down a series of trays, increasing the surface area of the water and promoting the exchange of gases. Aeration also removes undesirable gases such as radon. Aeration is similar to the natural process that occurs when a stream flows through rapids or over falls.

2. Softening
The CRWD adds slaked lime to the water. This softens or reduces the minerals that typically make water “hard.” Excessive hardness increases soap use, deposits scale in water heaters and boilers, interferes with some industrial processes and sometimes gives water an unappealing taste and odor. Resulting lime residual materials are removed and applied to farmland as soil conditioner. Learn more about this process »

3. Recarbonation & Chlorination
The CRWD lowers water pH by adding carbon dioxide and adds chlorine to disinfect the water. The chlorine helps ensure our water’s microbiological safety by killing disease-causing organisms. The Department also adds a trace amount of ammonia to complete the disinfection process.

4. Filtration
Water is then passed through a sand and gravel filter bed, removing any remaining suspended matter.

5. Fluoridation & Phosphate Addition
After filtration, the CRWD adds fluoride to promote children’s dental health. Learn more about this process »

Phosphate is also added to chemically stabilize the water and lessen the possibility that lead will leach out of pipes and into tap water. The CRWD is currently involved in an investigative study to optimize this process. Learn more about this process »

6. Ultraviolet (UV) Disinfection
Water passes through a chamber where it is exposed to ultraviolet light.  The UV energy instantly damages the genetic material (DNA) of microorganisms in the water.  Unable to reproduce the microorganisms no longer pose a health risk. Learn more about this process »

7. Distribution
From here, finished water is pumped directly into the three principal water distribution systems that serve homes and businesses throughout the City.

8. Reserves
Water not immediately consumed flows into storage tanks for use when demand exceeds plant pumpage. Water stored in elevated tanks helps stabilize the pressure in the distribution system and serves as an emergency reserve for fire protection

Watch a video explaining ultraviolet light disinfection:

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