Evansville to Switch Water Disinfectant Starting May 10 Through June 28

(May 3, 2021) - It happens twice a year, in spring and summer. The Evansville Water and Sewer Utility (EWSU) will temporarily change the disinfectant used in the water treatment process. This brief, scheduled change in disinfectant is a standard water treatment practice to keep water mains clean and free of potentially harmful bacteria throughout the year.

Beginning Monday, May 10, and continuing through Monday, June 28, 2021, EWSU will be using free chlorine rather than the regularly used disinfectant (chloramine) during this  period. This is the first of two disinfectant switchovers, with the second switch coming in August. A separate notice for the second switchover will be issued.

Here’s what you should know

  • What is Chloramine?

Chloramine is a disinfectant used in drinking water to remove bacteria and viruses that can make you sick. It is made up of chlorine and ammonia. EWSU has used chloramine as the disinfectant in its water treatment process since 1999.

  • What is Free Chlorine?

Free chlorine is a slightly more potent disinfectant than chloramine, and it is used to remove more resistant bacteria and viruses that may be found in the water distribution system.

  • Why would EWSU Convert from Chloramines to Free Chlorine?

State drinking water guidelines recommend that utilities using chloramine periodically switch to free chlorine for a while. The temporary use of chlorine will ensure that a proper level of disinfectant is maintained throughout the network of water mains and pipes that deliver your drinking water.

Free chlorine is a more aggressive disinfectant than chloramine. This temporary change in the water treatment process denies bacteria the ability to form resistance to the usual disinfection treatment process. Switching to free chlorine is a proactive step to ensure that we maintain optimal disinfectant levels in the water distribution system. As always, the drinking water will be regularly monitored to ensure that the water delivered meets or exceeds federal Safe Drinking Water Act standards.    

  • Why Does EWSU Use Chloramines Most of the Year?

While chlorine is an effective disinfectant, using chlorine alone creates byproducts  that the U.S. Environmental Protection Agency regulates. These byproduct levels can be significantly and cost-effectively reduced through the use of chloramine. Also, chloramine has less smell than chlorine and remains in the distribution system longer to prevent bacterial growth. As such, chloramine is a better long-term choice as a regular disinfectant.

  • Will I Notice a Difference in My Water?

During this period, some customers may notice a slight change in the taste or smell of their tap water. Free chlorine may have more of a chemical odor, slightly like that of swimming pool water. Each customer has his or her sensitivity level to the taste or smell of free chlorine. Many detect no change at all. The mild chlorine taste and smell are typical and pose no health risk.

  • Are Free Chlorine and Chloraminated Water Safe?

Yes, both chlorine and chloramine are effective and safe for people and animals for drinking, cooking, bathing, watering the garden, and all other standard uses. However, precautions should be taken to remove or neutralize chloramine and free chlorine during the kidney dialysis process, in the preparation of water for fish tanks and ponds, and for businesses requiring highly-processed water. A dechlorination procedure optimized for chloramine removal will work equally well with free chlorine.

People and businesses that typically take special precautions to remove chloramine from tap water (such as dialysis centers, medical facilities, and aquatic pet owners) should continue to take the same precautions during the temporary switch from chloramine to free chlorine.

Most customers will not need to take any precautions as the water remains safe to drink and is treated according to state and federal standards.

  • Information for Kidney Dialysis Patients

Just like chloramines, free chlorine must be removed from water used in kidney dialysis machines. EWSU has contacted representatives from the medical community to inform them of this temporary conversion. We advise customers who are dialysis patients to call their physicians or dialysis centers if there are any questions.

  • Information for Fish Owners

Like chloramine, free chlorine is toxic to fish. Fish owners need to remove chlorine, ammonia, and chloramine from the water before using with tropical fish. Local pet stores carry water conditioners that remove chloramine and free chlorine. If customers have questions, we recommend contacting their pet store for information and detailed instructions.


About EWSU
Evansville Water and Sewer Utility (EWSU) provides high-quality, safe, and dependable water and sewer services to more than 63,000 customers in Vanderburgh County and parts of Gibson, Posey, and Warrick counties. EWSU maintains more than 1,000 miles of water lines, 800 miles of sewer lines, 6,000 hydrants, seven water storage facilities, two wastewater treatment plants, and one water filtration plant. The utility also manages the City’s street sweeping and trash and recycling contracts. EWSU meets or exceeds all state and federal Safe Drinking Water Act standards while protecting land and water resources for future generations.