It’s over 100 years since chlorine was introduced to drinking water in the U.S. It’s often described as one of the most significant advances in human health in the last century. Its ability to disinfect, to reduce taste and odor, iron and manganese oxidation, and remove some organic chemicals makes it the logical choice for most urban water utilities. And.. it’s cheap!
Today, utilities have alternatives to chlorine, such as ozone and chlorine dioxide for primary disinfection, or chloramines for secondary disinfection in the distribution system. Utilities have used chloramines since the 1930s. Probably one in five people in the U.S. drink water treated with chloramines.
The Chloramine Family and its Nasty Neighbours
The U.S. EPA gives two choices for disinfectant residual: chlorine or chloramine. Many major water agencies are changing to chloramine so they can meet current and anticipated federal drinking water regulations. Since the Safe Drinking Water Act of 1974, utilities around the country have made changes to their disinfection strategies to meet more stringent regulations for either microbial contaminants or disinfection byproducts (DBPs). Both chlorine and chloramine react with other compounds in the water to form DBPs.
Chlorine forms many byproducts, including trihalomethanes (THMs) and haloacetic acids (HAAs), whereas chloramine forms a significantly lower amount of THMs and HAAs but also forms N-nitrosodimethylamine (NDMA), still unregulated yet suspected of being carcinogenic. The EPA ‘is studying it’. NDMA is formed when chloramine decays in the water and releases ammonia through a process called nitrification, which converts to nitrosamines from ammonia-oxidizing bacteria.
Whatever disinfectant is used, types and concentrations of DBPs typically vary from each utility depending on source water, levels of organic matter, temperature, amount of disinfectant used and more.
- Chloramine lasts than chlorine longer in the reticulation system before dissipating.
- Less chlorine is required for the residual to reach the last house and can eliminate the problem of high dosage requirements affecting the homes at the front of the distribution system with an objectionable end product.
The term “chloramine” is commonly used, but the actual compound used is monochloramine.
Monochloramine is a different chemical from dichloramine and trichloramine, (chloramines formed by other complex chemical reactions). Dichloramine and trichloramine are sometimes found in and around indoor swimming pools and can cause skin, eye and respiratory problems. It often is formed when chlorine in the pool reacts with ammonia released from human bodies’ perspiration and other organic matter.
The 3 forms of chloramine are chemically related and, if water conditions are favourable, can be converted into each other.
The species that predominates is dependent on pH, temperature, turbulence and the chlorine-to-ammonia ratio.
After a day or so with no changes in conditions, monochloramine in a water system slowly degrades to form dichloramine and some trichloramine. Chloramines can be respiratory irritants, with trichloramine being the most toxic. In contrast to what some water utilities claim, it is impossible to have only monochloramine, and it is not unusual in water systems for di- and trichloramines to occur.
Chlorine is a strong oxidizer and can form stable, passivating oxide scales that limit the release of metals into drinking water. Chlorine-induced scale consists of iron oxide in iron pipe, lead oxide in lead pipe, and copper oxide in copper pipe. Chloramine is a weaker oxidizer. The corresponding scale buildup observed with chloramine, are composed of less stable compounds, including iron oxide and hydroxide and carbonates in iron pipe, lead carbonate in lead pipe, and copper oxide in copper pipe. Chloramines react with certain types of rubber hoses and gaskets, such as those on washing machines and hot water heaters. Black or greasy particles may appear as these materials degrade.
Chloramination, if not properly optimized, can result in nitrification in the presence of bacteria. Nitrification, in turn, can lower the pH of the water, which can increase corrosion of lead and copper.
The Bad News
So far, research indicates that certain DBPs may be harmful. There is the possibility of certain byproducts being linked to increases in cancer, including bladder cancer. Other research suggests that certain DBPs can be linked to liver, kidney, central nervous system problems and reproductive effects. Still more research indicates that certain DBPs can be linked to anemia.
Scientists hailing from many organizations have conducted research on the effects of DBPs. In some cases, research results are contradictory; some studies show links to adverse health effects and others do not.
Because the chloramine conversion reaction is catalytic in nature, activated carbons that exhibit enhanced catalytic activity are more efficient. In theory, monochloramine removal is a two-step reaction. Chloramine removal is apparently enhanced with catalytic activated carbons because of their high number of catalyst sites compared to conventional carbons. The chloramine removal efficiencies of catalytic carbons cut required contact time, extend bed life and enable the use of smaller equipment. These advantages translate into cost savings for the end user without the sacrifice of the carbon’s capabilities.
Hopefully you can see why we’ve selected catalytic carbon vs. standard carbon. We can’t tell whether you are being supplied with chlorine or chloramines, but catalytic carbon covers both possibilities more efficiently and more safely.
Whatever water filter system you are evaluating, make sure to ask what form of carbon they use. If possible, ask them for test data for the life of the filter rather than a once-only ‘Day One’ test. The UltraStream has been tested for the expected life of the filter so what you see in the test results are what you get.