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12/3/2024
WT Staff
 Got water questions? Give us a call at 877-52-WATER (877-529-2837), or email us at info@watertoday.ca
December 3, 2024 944 am PST
Disinfection of drinking water, managing the unwanted by-products
California State Water Resources Control Board is responsible for the oversight of the state's licensed drinking water facilities, supporting the national EPA Safe Drinking Water Act regulations and beyond. The State of California regulates over 7400 licensed facilities to some of the highest drinking water standards in the USA, posting one of the highest facility compliance records in the country at 93.9%. When a microbiological compliance breach occurs, a boil water advisory is issued for the impacted customers, WTCAL.us posts these events on the map to the right in yellow.
Compare the California drinking water facilities to the global record: in 2022 the World Health Organization (WHO) estimates 73% of the world population, approximately 6 billion people were served by safely-managed drinking water facilities. For Californians, the percentage served by SDWA compliant facilities is 99.98%.
The need for disinfection
Microbiologically-contaminated drinking water is a reality for 27% of the global population. Even in North America, the best managed and SDWA-compliant drinking water facilities can experience incidents of potential microbiological contamination. Power outages, loss of pressure in the distribution lines, pump failure, rupture of aging water mains, construction accidents and scheduled maintenance work can introduce contamination, prompting the boil water advisories, posted when they occur with yellow tags on the map to the right.
According to the WHO, contaminated water transmits "diseases such as diarrhoea, cholera, dysentery, typhoid and polio and is estimated to cause approximately 505 thousand diarrhoeal deaths (globally) each year." The disinfection of drinking water remains key to preventing such illnesses and deaths. Highly trained water operators along with a robust system of monitoring and reporting water quality, inspections and prompt public notice of boil water orders maintains the integrity of public drinking water.
See how drinking water facilities of California compare with Georgia, New York, Ohio and Louisiana, here.
Even where drinking water facilities are well managed, extreme weather events and flooding can overwhelm public water supplies with contamination. Municipal sanitary sewer works are often located in the lowest elevation areas, these can be the first sites to flood during heavy rains and extreme weather events such as Hurricane Helene. WT documents sewage spills reported to or by state authorities, pinning the locations on the maps in pink. In 2022, the sewage spills reported in just one area of Georgia tallied up to more than 10 million gallons of raw sewage entering a single water body. Municipalities all over the USA are investing in programs to prevent sewage spills, to expand the storage capacity of combined sanitary and storm sewers, or to separate sewage from the stormwater collection infrastructure. Until these persistent issues are addressed, contamination from the combined overflow incidents will continue, often unreported. Disinfection of drinking water remains a critical issue. Register for the EPA National Pollution Prevention and Training, here.
According to the Centers for Disease Control, chlorine was introduced to kill germs in drinking water in 1908. Chloramine, a compound of chlorine and ammonia was first used as a disinfectant for public drinking water in 1929. By 1979, the EPA recognized the need to amend the Safe Drinking Water Act to monitor for a new set of troubling contaminants, the by-products of disinfection.
Centers for Disease Control explains, "Disinfection byproducts are chemicals made when chlorine or chloramine come into contact with dirt or other materials in water. At high enough levels, disinfection byproducts can cause health problems over time." When the disinfection by-products trihalomethane and/or haloacetic acids are found in excess of the maximum contaminant level (MCL), the drinking water facility must notify the water customers and report the exceedance to the authorities. A sensitive persons advisory is issued in these cases. According to the Ohio EPA warning for excess trihalomethane, "You do not need to use an alternative (e.g. bottled) water supply. However, if you have specific health concerns, consult your doctor." Under the health impacts, the Ohio EPA guidance to the public states "some people who drink water containing trihalomethanes in excess of the MCL over many years may experience problems with their liver, kidneys, or central nervous systems, and may have an increased risk of getting cancer."
The Nov 21 2024 issue of the journal, Science contains a research paper by Fairey, et al identifies what has been known as an unidentified contaminant. See our coverage of the "chloronitramide anion", here. The isolation of this substance, identification and study of impacts may lead to a future amendment to the regulations for drinking water.
As the EPA studies new contaminant threats to public drinking water, the SDWA is periodically amended. In April 2024, a suite of six per-and polyfluoroalkyl substances were added to the list of contaminants that drinking water facilities will be required to monitor and report, with legally enforceable maximum contaminant levels. US licensed drinking water facilities have until 2029 to establish the capacity for compliance with the amended regulation. Funding has been established to assist with the cost. See the details on the latest SDWA amendment, here.
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