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Drinking water contaminants of concern
Drinking water can become contaminated by a variety of germs and chemicals. The people most likely to get sick from contaminated drinking water are infants and young children, older adults, people who are pregnant, and people who have weakened immune systems. For detailed descriptions of contaminants that can find their way into drinking water, please visit the WA State Dept. of Health webpage on Drinking Water Contaminants and the CDC webpage on Water Contamination and Diseases. Additionally, some contaminants pose little-to-no risk to human health but can create a nuisance making water undesirable or create issues with your plumbing and water system. The following are some contaminants of concern found in King County:
Coliform bacteria
Coliform bacteria are organisms found in the environment and in the feces of all warm blood animals and humans. While coliform bacteria will not likely cause illness, they are indicator organism, meaning that their presence in drinking water indicates that disease causing organisms, such as harmful strains of E. coli, could be in the water. The presence of coliform bacteria indicates that germs may be getting into the water supply somehow.
E. coli
E. coli is a fecal coliform that may be found in the intestines of humans and animals. While most strains of E. coli are harmless, some strains, such as E. coli O157, can cause serious illness. E. coli can enter water supplies as fecal matter from an infected animal or human gets in to water. Common symptoms associated with disease-causing strains of E. coli are stomach pain, diarrhea, and vomiting.
Arsenic
Arsenic is a naturally occurring chemical found in the earth that can also be the result of industrial and agricultural pollution. The US EPA has set the maximum level for arsenic in drinking water to 10 parts per billion (ppb), which is intended to prevent the negative health effects of long-term exposure. Chronic exposure to arsenic in drinking water can increase risk of cancer and contribute to issues with heart and lung disease, diabetes, immune system response, skin irritation, neurological impairments in adults and neurological delays in children. Children, people who are pregnant, and children in utero are particularly vulnerable to the health effects associated with long-term exposure to arsenic in drinking water.
Nitrate
Nitrate is a naturally occurring chemical and is essential for plants and animals. Large amounts of nitrate may end up in the environment from fertilizers and animal waste. Nitrate easily dissolves in water which can move through the ground and into aquifers. The Washington state standard for nitrate in drinking water is 10 parts per million (ppm). Babies are at particularly high risk when ingesting high levels of nitrate. Infants who consume high levels of nitrates can develop a serious condition called metheglobinemia, or "blue baby syndrome", in which their blood has trouble carrying oxygen. Damaged wells, flooding, agriculture, concentrated animal activities, and nearby waste disposal can contribute to heightened levels of nitrate in drinking water.
Iron
Iron in drinking water is not a serious danger but it can change the color, taste, and smell of water. The EPA has listed iron as a secondary contaminant, meaning there is little health risk. Signs of drinking water with high levels of iron include red/brown/yellow color, metallic taste, clogged pipes, and a bad smell. Certain kinds of bacteria eat iron while creating a slime that is capable of clogging plumbing fixtures and giving off an odor. Iron-related bacteria is not harmful, but it can be disturbing and make the water undesirable.
Manganese
Manganese (PDF) is a naturally occurring mineral found in rocks that can dissolve into water. Ingesting large amounts of manganese in drinking water can cause negative health effects. Manganese can make your water look, taste, and smell undesirable while staining household fixtures and building up in pipes. Infants are the most at-risk age group for excess manganese exposure which can result in developmental, learning, and behavioral problems. The EPA has set a health advisory limit to 300 parts per million (ppm) and aesthetic standard to 50 ppm. It is advised infants consume water that is has nitrate levels of 100ppm or less.
Copper
Copper is a naturally occurring mineral found in soil. While copper is an essential dietary mineral, too much of it can cause kidney and liver issues as well as anemia. Water sources may be contaminated by industrial pollution, mining, and weathering of copper bearing rock formations. More commonly, people are exposed to copper in their drinking water from copper in household plumbing corroding and getting into their water supplies.
Lead
Lead is a chemical element that can be poisonous when consumed. While lead in drinking water is not a common source of lead poisoning in King County, it may come from water fixtures in household plumbing and pipes. Infants and children are the most vulnerable to lead poisoning and exposure has been linked to damage to the central nervous system and learning disabilities.
Disinfection byproducts
Many large water systems add chlorine to drinking water to kill or inactivate harmful germs. During this process, the chlorine interacts with organic matter and creates chlorine disinfection byproducts (DPBs). There are several types of DBPs that the EPA has set limits for, and chronic exposure to DBPs could result in increased risk of cancer, liver damage, and decreased nervous system activities.
PFAS
Per- and polyflouroalkyl substances (PFAS) are a type of human-made chemicals known for their water-resistant and non-stick properties that can be found in things such as firefighting foams, weatherproof outdoor gear, food packaging, and non-stick pans. These "forever chemicals" do not break down easily in water or soil an can remain in the environment, pollute water source, and end up in drinking water. While scientific research is still being conducted on how PFAS impacts people's health, what we do know is that PFAS negatively affects growth and development, thyroid function, immune response, and reproductive health.
Cryptosporidium
Cryptosporidium is a parasite occurring in the feces of infected animals and humans that can cause diarrhea, abdominal cramps, headaches, nausea, vomiting, and fever. Groundwater system and large water systems that perform rigorous monitoring and disinfection are protected against cryptosporidium. However, individuals and small community water sources relying on creeks, streams, or lakes may be more susceptible to cryptosporidium.