Some people are more sensitive than others to chemicals and changes in their environment. Individuals who have health concerns should seek medical advice from their healthcare provider before contacting their local health department external icon. Dialysis centers must treat the water to remove all chemical disinfectants, including chlorine and chloramine, before the water can be used for dialysis. Home dialysis users should consult the machine manufacturer for instructions on how to properly treat their water before use.
At this level, harmful health effects are unlikely to occur. Chlorinated water can taste and smell different than untreated water. Some people like the taste and smell of chlorinated water, and others do not. Taste and smell problems may arise depending upon the water quality and amount of chlorine in the water.
Chlorine and chloramine are toxic to fish, other aquatic animals, reptiles, and amphibians. Unlike humans and other household pets, these types of animals absorb water directly into the blood stream. Chlorine can be removed from water by letting it sit out for a few days or by buying a product at your local pet store that removes the chlorine.
Ask your local pet store about methods of removing disinfectants from water for these pets. The small amount of chlorine added to water will not affect other pets such as mammals and birds and can be used regularly for watering and bathing animals. The U. Environmental Protection Agency EPA allows drinking water treatment plants to use chloramine and chlorine to disinfect drinking water. Water system pipes develop a layer of biofilm slime that makes killing germs more difficult. Water providers may temporarily switch from chloramine to chlorine disinfection to help remove this slime layer.
Chloramination is the process of adding chloramine to drinking water to disinfect it and kill germs. It is sometimes used as an alternative to chlorination. Chloramines are a group of chemical compounds that contain chlorine and ammonia.
The particular type of chloramine used in drinking water disinfection is called monochloramine which is mixed into water at levels that kill germs but are still safe to drink. Studies indicate that using or drinking water with small amounts of chloramine does not cause harmful health effects and provides protection against waterborne disease outbreaks. A normal level for drinking water disinfection can range from 1. Individuals who have health concerns should seek medical advice from their healthcare provider before contacting their local health department.
Contact your local health department for more information external icon. At these levels, harmful health effects are unlikely to occur. Research shows that chloramine and chlorine both have benefits and drawbacks.
Chlorine is a highly effective method of disinfection. Chlorine is also used up quickly in water systems. Pre-chlorination is found to remove tastes and odours and control biological growth throughout the water treatment system, thus preventing growth in the sedimentation tanks and the filtration media.
This controls the biological growth, removes iron and manganese, removes taste and odours, controls algae growth, and removes the colour from the water. The most common stage for chlorination is as a final treatment step to disinfect the water and maintain chlorine residuals that will remain in the water as it travels through the distribution system. Chlorinating as a final step is more economical because a lower CT value is required, as by the time the water has been through sedimentation and filtration, a lot of the unwanted organisms have been removed, so less chlorine and a shorter contact time is required to achieve the same effectiveness.
Secondary disinfection may be applied to the treated water as it leaves the treatment plant or at rechlorination points throughout the distribution system, to introduce and maintain a chlorine residual in the drinking water distribution system.
Overall, a chlorine residual provides two main benefits:. A chlorine residual may also reduce the risk of recontamination in the event of an intrusion into the distribution system. A number of different by-products can be produced from reactions in the chlorination process. Some by-products, such as chloramines, are beneficial to the disinfection process because they also have disinfecting properties.
However, there are several undesired compounds that may be produced from chlorine reacting with natural organic matter such as humic and fulvic acids, which are generated from the decay of organic matter:. In order to avoid the formation of CDBPs, it is recommended to remove organic precursors or optimise the treatment system to so that chlorine is added after organic precursors have been removed.
While chlorination can help improve taste and odour through the reaction with organic materials and iron, it can also generate chlorinous flavours caused by the presence of the disinfectant itself or by the occurrence of other CDBPs formed by the reaction with other compounds in the water. For example, the reaction of chlorine with certain nitrogen compounds e. Chlorophenols can also be formed at the plant or in the distribution system and can impart taste and odours to the water.
The consequence of these compounds in drinking water is consumer dissatisfaction, turning to other water sources such as bottled water , purchasing home filtration devices MACKEY , and the rejection of a water source that is actually safe to drink. This is particularly a problem when no other safe drinking water sources are available.
While chlorination can result in CDBPs that pose health risks and cause taste and odour problems, risks to health from these by-products are extremely small in comparison with the risks associated with inadequate disinfection. However, some CDBPs are carcinogenic and should be avoided by removing organic precursors before chlorination. Despite these risks, the effectiveness in killing pathogens far outweighs the risk of CDBPs. While most microorgansisms are rapidly deactivated by chlorine e.
Giardia and Cryptosporidium , and thus are not killed when chlorine is added to water. If these pathogens are present in large concentrations, additional treatment is needed such as membrane filtration or boiling for more information pathogens in drinking water, see pathogens and contaminants.
Chlorine is a low-cost way to effectively disinfect drinking water. Centralised chlorination as primary disinfection is most economical when added as a final treatment step, as less chlorine is needed to achieve the same level of disinfection. Chlorination is an effective water purification method, but the presence of inorganic compounds e. Therefore, removal of these compounds before the addition of chlorine is recommended, or other water purification methods preferentially employed, such as solar disinfection see solar pasteurisation , UV tubes , and SODIS , membrane filtration , or boiling to kill pathogens.
To ensure effectiveness and prevent recontamination , a chlorine residual should be maintained throughout the distribution system. Water leaving a treatment plant should be tested daily for chlorine residual, turbidity, total coliforms, and E.
In the distribution system, the presence of adequate chlorine residuals should be confirmed when sampling for total coliforms and E.
This magazine article focuses on the formation and risks associated with various chlorine disinfection by-products, emphasizing the fact that the risks associated with these by-products must be balanced with the benefit of effectively eliminating water borne diseases. This position paper provides an overview discussion on the practice of chlorination in water treatment.
The discussion covers the following topics: general chlorination practice, chlorine disinfection capabilities, by-product formation, current regulations and use of alternative oxidants for disinfection. This document gives an overview on the role of chlorination in disinfecting drinking water. It includes information on chlorine and waterborne disease, disinfection by-products, and compares chlorine to alternative disinfection methods such as ozone and ultraviolet radiation.
This webpage by the U. EPA gives basic information about the role of chlorine in disinfecting drinking water in the U. This document provides information about the consumer perception of drinking water regarding water quality, taste, and odor and how these factors influence consumer perception about the safety and quality of drinking water.
This technical factsheet gives basic information about chlorine, how chlorine is added to our drinking water, and about chlorine disinfection by-products.
This case study describes how a drinking water treatment plant reduced the number of complaints about the taste and odour of drinking water and reduced the formation of trihalomethanes a disinfection by-product by pre-chlorinating raw water with chlorine dioxide. This short case study describes how a drinking water treatment plant was able to remove manganese and reduce turbidity by applying chlorine dioxide to raw water as a pre-oxidant.
This article describes how safe water is supplied and distributed in the Netherlands without the use of chlorine in primary or secondary disinfection steps. This training guide provides practical information on the chemistry behind chlorination, application of chlorination in a treatment plant, and chlorine safety, including a section of study questions. Your public water system is the first line of defense against waterborne disease.
View step-by-step how water is treated and delivered to your home or business as water that is safe to drink. Your drinking water is inexpensive compared to other household costs. They vary in the amount of chlorine used. Batch disinfection treats water in batches when the chlorine demand fluctuates. It is especially useful for cisterns, holding tanks, or during emergencies or other special situations.
Three tanks, each capable of holding a two- to three-day water supply, are alternately filled. The water is treated and used as needed. Simple chlorination maintains a low level. The residual should be measured at the faucet farthest from the chlorine source.
When the necessary contact time is unattainable, super-chlorination followed by dechlorination chlorine removal is an option. Super-chlorination produces a free chlorine residual of 3. At this concentration, the necessary contact time is reduced to less than five minutes for water at pH 7. Super-chlorinated water has a strong chlorine smell and taste that is removed with an activated carbon filter following chlorine treatment.
If the water contains dissolved iron, manganese, or sulfur, it may be necessary to install a cartridge sediment filter before the activated carbon unit to prevent clogging.
Shock chlorination is recommended when a well is new, newly repaired or temporarily contaminated. If bacteriological problems persist after one or two shock chlorination treatments, you may consider a continuous disinfection system or a new water source. The effectiveness of chlorination depends on the amount of chlorine used.
The amount is controlled by adjusting the equipment or by changing the amount of chlorine added for batch disinfection. Various kinds of injection devices and pumps are used to chlorinate a private water supply. The injection device should operate only when the water pump is functioning, and the water pump should shut off if the chlorinator fails or if the chlorine supply runs out. When deciding on a location for chlorination equipment, ensure that: electric sources are conveniently located; adequate ventilation is provided to exhaust chemical fumes and cool any motors; the area is relatively free of dust and dirt, which can collect on movable parts and lead to malfunction; the area is protected from excessive sunlight or freezing; the area has easy access for maintenance and refilling; and, if using a chemical tank, the tank is located as close as possible to the feeder.
Maintaining a chlorination system may involve periodically checking for loose, worn, missing, or broken parts; lubricating the entire system semi-annually; cleaning all surfaces showing corrosion; refilling chlorine supplies; and cleaning any clogged orifices. Be sure to unplug any power cords before maintenance. Both solid and liquid forms of chlorine can irritate the skin and are poisonous in concentrated form.
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