WATER QUALITY GLOSSARY

E. coli, or Escherichia coli, is a type of bacteria that can be found in the environment, foods, and intestines of people and animals. While most strains are harmless, some can cause serious illness when they enter the water supply. When it comes to drinking water, E. coli is considered a key indicator of fecal contamination, meaning that if it’s present, there’s a chance other harmful bacteria, viruses, or parasites could be as well.

Monitoring and controlling E. coli in drinking water is essential because its presence signals that the water may not be safe to consume. This makes regular testing and proper treatment methods vital for protecting public health. Both the U.S. Environmental Protection Agency (EPA) and the World Health Organization (WHO) have set strict guidelines that call for zero detectable E. coli in public water systems. In short, even a small amount of E. coli in your drinking water is considered unsafe.

E. coli is a naturally occurring bacterium that lives in the intestines of humans and warm-blooded animals. Most types of E. coli are harmless and even play a role in digestion. However, certain strains, like E. coli O157:H7, can cause serious foodborne or waterborne illness.

E. coli can enter the water supply when fecal matter from humans or animals gets into rivers, lakes, or groundwater sources. This can happen in several ways, such as from failing septic systems, stormwater runoff, or agricultural activities where manure is used as fertilizer.

Natural Sources:

• E. coli can be found in soil and surface water when animal feces are present in the environment.
• Wildlife living near water sources can introduce E. coli through droppings that eventually wash into lakes or rivers.

Human-Made Sources:

• Leaking or overflowing septic tanks are a common cause of contamination in rural areas.
• Runoff from farms, especially where livestock are raised or manure is applied to crops, can carry E. coli into nearby water sources.
• Wastewater treatment plants that aren’t functioning properly or are overwhelmed during storms may release untreated sewage into rivers or groundwater.
• Cracks in old or damaged plumbing systems can allow E. coli from contaminated groundwater to enter your tap water.

Environmental Factors:

• Heavy rainfall can increase runoff, carrying bacteria into water bodies.
• Flooding can overwhelm water treatment systems and spread contaminants widely.
• Shallow wells and unprotected water sources are more vulnerable to contamination.

While most people recover from E. coli infection without any lasting issues, certain strains can cause more severe symptoms and complications.

Short-Term Health Effects of E.Coli

• Nausea and vomiting
• Stomach cramps
• Diarrhea (often bloody)
• Fever

Long-Term Health Risks Of E.Coli

• Some strains, like E. coli O157:H7, can lead to hemolytic uremic syndrome (HUS), a serious condition that affects the kidneys and can be life-threatening.
• Other long-term effects may include high blood pressure or chronic kidney disease in rare cases.

Vulnerable Populations:

• Infants and young children
• Older adults
• Pregnant women
• Individuals with weakened immune systems

For these groups, even mild exposure to E. coli can lead to more severe outcomes, making prevention even more critical.

Visible Signs: Unfortunately, E. coli cannot be seen, tasted, or smelled in water. There are no obvious warning signs, contaminated water often looks completely normal.

Testing Methods:

• Laboratory Testing: This is the most accurate way to detect E. coli. Water samples are sent to certified labs where specific bacterial presence is measured.
• Home Testing Kits: Some home kits can detect coliform bacteria (a group that includes E. coli), but results are less precise. If a home test shows possible contamination, follow up with lab testing.

Acceptable Limits:

• The EPA and WHO both set the safe limit for E. coli in drinking water at zero. Any detection means the water is unsafe to drink.

If your water tests positive for E. coli, don’t panic, but do act quickly.

Water Treatment Methods:

• Boiling: Bringing water to a rolling boil for at least one minute (or three minutes at higher altitudes) kills E. coli and most other pathogens.
• Chlorination: Chlorine is widely used in public water treatment and is effective against E. coli. Homeowners with private wells can use chlorine shock treatment, but it should be done carefully.
• UV Light Purification: Ultraviolet light systems can destroy E. coli without chemicals, but water must be clear for UV to be effective.
• Filtration: Certain filters, like reverse osmosis systems or those labeled “microbiological water purifiers,” can remove bacteria, including E. coli.

Comparing Water Filtration Systems:

Prevention Tips

• Test your well water at least once a year.
• Inspect and maintain your septic system regularly.
• Avoid using water from untreated or untested sources.
• Protect wells from surface water runoff and contamination.