Chloramine, Chlorine, Lead and Pipes: How Water Treatment Turned Toxic
What do the most Common Water Treatment Chemicals–Chlorine and Chloramine–Have to do with Lead in Water?
Flint’s water crisis is a disastrous story of negligence and environmental injustice. After the city switched its water source, lead–a neurotoxic metal– began leaching from pipes into people’s drinking water. Families drinking tap water found their children had increased blood lead levels. While the mayor of Flint announced in April that the water is finally safe to drink again, many are still skeptical and concerned.
How did simply switching from one river to another river have such drastic effects on people’s water quality? TapScore has written this guide to help you understand why switching water sources (e.g. in Flint) or water disinfectants (in the case of D.C. water) can cause lead to leach from pipes, what the dangers are, and how to protect yourself.
The Science Behind Lead in Flint and D.C.
To understand how lead leaches into water, we first need to know what water disinfectants are and how they can affect drinking water and human health. We’ll bring you through the science behind lead leaching in pipes through the stories of two different cities that made changes to their water: DC switched its disinfectant, while Flint switched its water source.
What Are Water Disinfectants?
The water that enters our homes is sourced from natural rivers, lakes, and man-made reservoirs. This water contains microorganisms, organic matter, soil, naturally occuring metals, and much more. The particulate matter and natural elements can be filtered out using physical barriers (e.g. reverse osmosis, carbon filtration, or other filtration methods). Microorganisms such as viruses and bacteria, however, must be killed using a disinfectant.
Chlorine is the most common disinfectant, but other disinfectants include chlorine dioxide, chloramines, UV light, and ozone. Since its introduction in the late 1800s, chlorine disinfection has become a major public health accomplishment, responsible for lowering the rates of infectious diseases such as typhoid, hepatitis, and cholera. Unfortunately, chlorine can also react with other naturally occurring materials in water to form disinfection byproducts (DBPs), which can be harmful to long-term health. Regulation of DBPs inspired the use of chloramines as an alternative disinfectant because it forms less of the most common forms of DBPs. Chloramines are formed when ammonia is added to chlorine. But, as you may have guessed–chloramine has its own unintended consequences.
Switching from Chloramine to Chlorine
D.C. Water and Sewer Authority (WASA) switched from chlorine to chloramine to reduce risk of DBPs. Shortly thereafter, high lead levels became a concern–but WASA was slow to respond and communication to households failed to adequately portray the urgency of the water quality problem. Researchers (led by Dr. Marc Edwards, who later got involved in Flint) found that, between 2001-2003, blood lead levels in children were four times higher when compared to the year 2000. Edwards claims that D.C.’s lead crisis is 20-30 times worse that of Flint – with lead concentrations found to be three times higher than those in Flint and 6.5 times the amount of people exposed.
After these findings, the city of D.C. reverted from chloramine back to free chlorine in 2004. They subsequently found that water lead levels in some samples were up to 10-fold lower and that almost all samples were below the EPA limit of 15 parts per billion (ppb). WASA concluded that chloramine was not solely responsible for lead leaching, but that the absence of chlorine resulted in pipe corrosion.
Lead (or any metal) leaching occurs when corrosive water enters an old pipeline and easily reacts with the metal pipes, creating metal ions that enter the water. Chlorine can combine with lead to form an oxide, which acts as a passivation (protective) layer on the inside of the pipes. This protective layer was protecting pipes from corrosive water.
These findings left D.C. with a public health predicament: neither option was entirely safe. Fortunately, compounds such as zinc orthophosphate exist to help corrosion control while using chloramine as a disinfectant by reacting with pipes to form a passivation layer. While D.C. has kept corrosion control on a priority list, thousands of lead pipelines still remain in the city’s distribution system.
Switching Water Sources
When Detroit Water and Sewer decided to switch its water supply from Lake Huron to the Flint River, the goal was to save costs. The city planned to switch to Karegnondi Water Authority pipeline to Lake Huron, but they had about a year before the project was complete–so they turned to Flint River. As we now know, engineers and officials failed to adequately manage the new source.
Health data showed that the number of children with lead levels in their blood had increased from 2.4% to 4.9% after the water source switch. One sample of Flint’s water had a record breaking level of 13,200 ppb lead, which is almost 900 times higher than the EPA limit. Lead is neurotoxic and dangerous for anyone, but especially for children because it can stunt their development and lead to behavioral problems and decreased IQ.
Lead leaching into drinking water shares similar water chemistry in Flint as in DC. The original water source that came in treated from Detroit had added orthophosphate to account for lead pipes, which created a strong passivation layer made of phosphate minerals. When Flint started treating its own water, they did not add orthophosphate and they did not adequately control the pH of their new water. When pH is too low (more acidic) in the absence of orthophosphate, lead can leach into the drinking water. The protection layer was quickly corroded, exposing Flint’s lead pipes and leading to lead leaching in water.
How can I protect myself?
An estimated 15-25 million homes are still connected to lead pipelines laid before they were banned in 1986. While most water systems actively manage the water quality and test for lead, the stories of Flint and D.C. illuminate how quickly things can go wrong. Hopefully, any metal leaching situation you may encounter is not as extreme. There are some things that you can do to protect yourself, depending on whether you are a private well user or are a public water system customer.
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