- City Departments
- Claude H. Dyal Water Treatment Plant
- Drinking Water
- Temporary Change to Disinfection Method
Temporary Change to Disinfection Method
Why the temporary change in disinfection method?
Why is drinking water disinfected?
Disinfection of drinking water is critical to protecting consumers from disease-causing microorganisms, called pathogens, including bacteria or viruses. Disinfectants are very effective at inactivating (or killing) pathogens and have enormously benefited public health. For example, the incidence of typhoid fever was reduced by 1,000-fold in the U.S. in the last century by implementing the disinfection of drinking water.
Public water systems are required to disinfect water prior to its entering the distribution system that carries it through pipes for delivery to consumers. Public water systems in Florida are also required to maintain a minimum amount of residual disinfectant throughout the distribution system to make sure levels of harmful microorganisms remain low. Treatment prior to distribution may utilize a number of different disinfectants, but a public water system is required to use either chlorine or chloramine in the distribution system. Cocoa Utilities Department uses chloramine.
What is chloramine?
Chloramine is a long-lasting disinfectant added to public drinking water for disinfection. It is formed by combining chlorinated water with small amounts of ammonia. It is commonly used for disinfection in many public water systems throughout Florida, the United States, and countries around the world.
Why does Cocoa Utilities Department use chloramine?
Chloramine is an effective disinfectant and persists over a long period of time, particularly in areas with high temperatures. This makes chloramine useful in Florida’s large distribution systems like Cocoa’s, which is spread out over a large geographic area.
Chloramine typically produces lower levels of regulated disinfection by-products (such as total trihalomethanes (TTHMs) or haloacetic acids (HAA5) compared to free chlorine, because it is less reactive with naturally occurring organic matter that may be in the water.
What are disinfection by-products?
Disinfection by-products (DBPs) are formed when disinfectants such as chlorine and chloramines react with natural organic matter in drinking water. The U.S. Environmental Protection Agency (EPA) regulates some DBPs, such as total trihalomethanes (TTHMs) and haloacetic acids (HAA5) to minimize their health risks. A challenge faced in drinking water disinfection is to protect the public from waterborne diseases while reducing public exposure to DBPs.
Is chloramine safe?
Yes, water disinfected with chloramine is safe for drinking, cooking, bathing, and everyday use. The EPA, the Centers for Disease Control, and the World Health Organization have determined that chloramine is a safe disinfectant and that water disinfected with chloramine within regulatory standards has no known or expected adverse health effects.
Chloramine, like chlorine, must be removed from the water prior to use in dialysis machines and can be harmful to fish and amphibians. However, proper filters and dechloramination products will address these concerns.
Why change disinfection method?
Nitrification and biofilm growth within distribution systems is an issue for drinking water treatment plants utilizing chloramine disinfection. Many chloraminated plants periodically switch to chlorine disinfection for several weeks to mitigate these issues.
What is a free chlorine conversion or temporary change in disinfection?
A free chlorine conversion occurs when a water system that typically uses chloramine removes ammonia (needed to form chloramine) from the treatment process, and disinfects the water with only chlorine. Chlorine is more effective than chloramine at inactivating certain types of bacteria. Excess ammonia, which can accumulate in a chloramine-treated distribution system over time, is a source of food for specific types of bacteria that are harmless to people. These bacteria can make it difficult for public water systems to maintain a disinfectant residual, which means that microorganisms that are harmful to people can grow.
Changing the disinfection method periodically is a common practice by many public water systems throughout the country to reduce the number of the bacteria so that a satisfactory disinfectant residual can be maintained throughout the distribution system. Chlorine conversions can be used as a preventative strategy or to stop nitrification (the microbial process that converts ammonia and similar nitrogen compounds into nitrite and nitrate), which can diminish water quality. According to a 2016 EPA survey, 25 to 40 percent of the utilities that use chloramine reported using this method to control nitrification.
Public water systems notify their customers prior to a chlorine conversion, because changes in taste and odor may briefly occur.
Why is my water system conducting a free chlorine conversion?
It is often conducted as a preventative maintenance measure to kill bacteria that can make the maintenance of disinfection residual problematic. A film can form in the distribution system piping that can contain bacteria which use ammonia as a food source. These bacteria in this film are harmless to people. When the water system stops adding ammonia, the bacteria starve. Therefore, a periodic conversion to free chlorine is effective for inactivating these types of bacteria in piping with biofilm by interrupting the supply of ammonia and can help prevent subsequent issues from occurring.
The conversion to free chlorine, in conjunction with increased flushing activities, assists in removing excess film from the distribution system and also starves these bacteria. The chlorine conversion helps the system return to an environment where the disinfectant residual can be maintained.
Are there any disadvantages to a free chlorine conversion?
Properly conducted free chlorine conversions can often cause the water to have a different taste and/or odor than when using chloramine for disinfection. Many customers notice the difference, but there are no health effects associated with the change in taste/odor. Once the water system has returned to using chloramine as the disinfectant, the taste/odor of the water will return to normal.