Haloacetic Acids in Drinking Water
What are haloacetic acids?
Haloacetic acids (HAAs) are a type of disinfection by-product that are formed when chlorine reacts with natural organic matter in the water. There are five significant HAAs in disinfected water and their combined concentrations is referred to as total HAA5.
What are the potential problems of having high HAAs in drinking water?
There is concern that long-term exposure to elevated levels of HAAs may pose a risk in the development of cancer.
What is the Canadian guideline for HAAs and when will it take effect?
A Canadian guideline for HAAs is under development. It could be developed, approved and take effect as early as spring 2007. Once the guideline is approved, it becomes an enforceable standard that Nova Scotia's regulated public drinking water supplies must meet. The United States has developed a guideline for HAAs of 0.060 mg/L (or 60 µg/L).
How may I be exposed to HAAs?
HAAs are present in chlorinated drinking water supplies due to the presence of naturally occurring organic matter in source water which reacts with chlorine. Water supplies relying on surface water generally have higher levels of chlorinated disinfection by-products than those relying on groundwater.
What if I have my own water well?
Most private well water supplies are not disinfected. The lack of chlorine disinfection means there should be no HAAs present.
Why don't we simply stop chlorinating our drinking water?
Without adequate disinfection of our water supplies, the health risks from micro-organisms would far outweigh the risks from HAAs. Drinking water is disinfected with chlorine to kill bacteria and viruses that can cause serious illnesses and deaths. In fact, chlorination of drinking water is one of the greatest achievements of public health protection having virtually eliminated typhoid fever, cholera and many other diseases.
How can HAAs be eliminated?
To meet a future proposed guideline for HAAs, municipalities will need to improve the removal of organic matter from the water before chlorine is added, modify the disinfection process, change other processes or switch to an alternate source of water. Nova Scotia Environment and Labour is working with Dalhousie University to investigate treatment strategies to help communities.
For more information contact:
Call the nearest Nova Scotia Environment and Labour office.
