E. coli & Water Health

South Carolina’s Waterway Health

Clean water is essential for recreation, public drinking water, aquatic life, agriculture, and other industries. South Carolina residents are fortunate to live in a state with 14 major reservoirs, each providing access to a wide variety of recreational activities from paddling to fishing and boating. Managing water quality requires commitment from all South Carolinians, from the mountains to the coast, including landowners, industries, cities, and local watershed groups and volunteers.

Why is Measuring Water Quality Important?

Water quality testing is an important part of managing and preserving healthy waterways. Poor water quality affects many aspects of our lives. Water quality refers to the chemical, physical, or biological characteristics of water. Simply put, it is a measure of the condition of water relative to its impact on one or more aquatic species, like fish and frogs, or on human uses such as drinking and swimming. The most common standards used to assess water quality relate to the health of ecosystems, safety of human contact, and suitability for drinking water.

Bacteria as a Pollutant

Fecal coliforms are bacteria associated with human or animal waste. The presence of fecal coliforms in water may not be directly harmful; however, it does indicate an increased likelihood of harmful pathogens in the water.

Escherichia coli (E. coli) is a type of fecal coliform bacteria commonly found in the intestinal tracts of warm-blooded animals. E. coli are so small that they can only be seen with a microscope or in colonies on a growth media under special conditions. E. coli is measured in our waterways to determine if the waterway is safely meeting standards for aquatic life, recreation, and drinking water.

Most E. coli are considered harmless, but there are a few specific strains that are pathogenic, meaning that they can cause disease in humans. Of these, the most well-known type is E. coli O157:H7, which is a dangerous strain known to contaminate foods like produce and beef. If a person does become sick from E. coli, the primary site of infection is the gastrointestinal tract and symptoms can include nausea, vomiting, diarrhea, and fever. (1) There was a 36-state E. coli outbreak in 2018, where romaine lettuce was contaminated by E. coli strain O157:H7.

E. coli in our Waters

The Canada Goose has an exceptionally high amount of E. coli recorded in their waste, relative to other animals.

The Canada Goose has an exceptionally high amount of E. coli recorded in their waste, relative to other animals.
Credit: Clemson University

Most strains of E. coli are not harmful to humans, but they are indicators of other harmful viruses or bacteria. E. coli in waterways can originate from the intestinal tracts of both humans and other warm-blooded animals, such as dogs, cats, livestock, and wildlife. The presence of E. coli in surface waters is an indication of recent sewage or animal waste contamination. Polluted runoff from rain events can carry E. coli from failing septic systems, animal waste in stormwater, leachate from dumpsters, and other sources. In urban watersheds, fecal indicator bacteria are significantly correlated with population. (2)

Ensuring “Drinkable & Swimmable” in South Carolina

The Clean Water Act promised waterways and policies that would maintain waterways as “drinkable and swimmable,” a task delegated to an authority in each state and tribal nation. In South Carolina, the SC Department of Health and Environmental Control (DHEC) is responsible for measuring water quality of surface waters. SCDHEC measures water quality by looking at a number of water quality indicators, including bacteria. (3)

If your drinking water is provided by a public water system they are required by law to notify you if your water is not safe. Local water systems issue out water quality reports that provide more information about drinking water in public systems.

Water that contains E. coli and other bacteria can be treated using chlorine, ultra-violet light, or ozone, all of which act to kill or inactivate E. coli. Systems using surface water sources are required to disinfect to ensure that all bacterial contamination is eliminated in drinking water. Groundwater-sourced systems are not required by law to disinfect the drawn water supply, although many of them do. (4)

People who obtain drinking water from a private well should have their water tested periodically. A lab will test the water for total coliforms first, which is a group of related organisms that are common in both the environment and the gastrointestinal system of animals. If the water sample from the well tests positive for total coliforms, the lab will then determine whether E. coli is also present. See HGIC Factsheet 3870 – Testing Drinking Water for more information. Although most strains of E. coli do not cause disease, users should not drink the water from the well unless it is disinfected. To disinfect water boil it for at least one minute at a rolling boil (longer for users who live at high altitudes). Wells may also be disinfected according to the procedures recommended by the local department. Well water should be monitored periodically after disinfection to make certain that the problem does not recur. (4)

A picture containing food, indoor Description automatically generated

A plate growing live E. coli bacteria, recognizable by their bright blue spot surrounded by an air bubble.
Credit: Clemson University

It is also important to test irrigation waters. There are federal, state, and local groups in South Carolina that test irrigation water quality to determine if it is safe. Growers of fresh produce will also test irrigation water to determine if there is E. coli present. (2) Irrigation waters are not equivalent to waters of the State.

Overall, E. coli is the most reliable indicator of fecal bacterial contamination of surface waters in the US. Water quality testing is required for water that is consumed for drinking and wastewater that has been treated and recycled for irrigation or discharged to surface waters. Rivers and streams that are used for recreation, such as fishing and swimming, are also regularly tested to ensure they are meeting adequate levels of E. coli. Acceptable levels of E. coli in South Carolina waters are given in Table 1. The concentrations of E. coli used in regulation are based on assessment of water a person consumes during different activities and the likelihood the person would become sick after coming into contact with the contaminated water.

Use of Water Level of E. coli permitted (CFU)
Drinking Water (Municipal Supply) Zero
Surface Water: Full-Body and Partial-Body Contact Geometric Mean of 126 Single Sample Maximum 349
*Agricultural Water: Sprout irrigation, water used for hand washing before and after harvest, water with direct contact on produce (including that used for making ice), water used on food-contact surfaces Zero
*Agricultural Water: Water directly applied to growing produce (other than sprouts) Geometric Mean of 126, and Standard Variation of samples is 410 or less
* These requirements are for agricultural waters derived from surface or groundwater. There is no requirement to test agricultural waters received from public water systems. More information on testing requirements can be found on the US Food and Drug Administration website, FSMA Final Rule on Produce Safety (5).

At the time of this publication, SCDHEC maintains approximately 800 monitoring stations, of which more than 300 failed to meet water quality standards for one or more parameters. Of these, 261 freshwater monitoring sites failed for E. coli concentrations. (6)

Managing Healthy Waterways is Everyone’s Responsibility

We all share a responsibility to protect our waters in South Carolina. There are numerous activities in your community that can ultimately impact surface water quality, as waterways and pollution mirror what happens on the land.

Here are some ways you can help keep rivers, lakes, and estuaries in South Carolina safe for recreation and wildlife:

  • Learn about your local water body or watershed.
  • Join a local watershed group or volunteer organization active in improving watershed management in your community.
  • Identify ways you can help prevent polluted runoff from your home, business, or farm.
    • Residential gutter downspouts that lead to roads and driveways can be diverted to grassy areas, plant beds, and away from your home. This is called “disconnecting impervious surfaces” and reduces the total volume of stormwater to your local waterway.
    • Capture stormwater runoff in rain barrels, rain gardens, vegetated swales, or other treatment.
    • Never flush “flushable wipes” if you send your wastewater to a wastewater treatment plant. After breaking down, flushable wipes come back together to create clogs and back-ups in our sewer pipes, often leading to spills. Dispose in the trash instead.
    • Dispose kitchen fats and grease in the garbage instead of down pipes. Similar to wipes, gelatinous masses form in our sewer systems, causing clogs, back-ups, and attracting rodents and more bacteria.
  • Pick up your dog waste in and around your neighborhood and dispose of it in the trash.
  • If you own a septic system, have it inspected every 3-5 years; professionals should be called immediately whenever there is standing septic leachate in the yard.
  • Use fencing to limit livestock access to streams and connected ponds.
  • The width of vegetation along a waterway is called a “buffer,” as this natural area slows stormwater runoff and effectively removes some of the pollution that would otherwise enter a waterway. Use vegetated buffers to minimize pollution, create habitat, protect the streambanks, and shade the river.
Adopt a Stream

SC Adopt-a-Stream invites interested residents to be certified in water quality and ecosystem monitoring through training events held in partnership with SCDHEC, Clemson University, and training partners across the state. More information available at

  • Call your city or county if you see manhole covers lifted up and flowing.
  • If you are interested in becoming more involved with citizen science efforts to protect surface waters in your area, visit the South Carolina Adopt-a-Stream (SC AAS) program website at The program began in SC in 2017 to create a network of watershed stewardship, engagement, and education through involvement. Volunteers provide baseline, non-regulatory information about stream conditions for communities, educators, and local government agencies to partner together to protect and restore waterways. Monitoring protocols include measuring for E. coli. The method used is affordable, scientifically valid, and informative. By measuring the presence of these bacteria on a monthly basis, volunteers can help local officials identify hot spots and areas for further monitoring and bacteria pollution prevention.


  1. U.S. Department of Health & Human Services. 2018. E. coli [Online] bacteriaviruses/ecoli/index.html. [accessed 17 April 2018].
  2. Griffith, J. F., Weisberg, S. B., and McGee C. D. 2003. Evaluation of microbial source tracking methods using mixed fecal sources in aqueous test samples. J. Wat. Health 1(4).
  3. SC Department of Health and Environmental Control. 2018. How DHEC Measures Surface Water Quality [Online] [accessed 16 May 2019]
  4. APEC Water. 2018. [Online] Drinking Water Contaminants – Eschirichia coli, E. coli [accessed 16 May 2019]
  5. US Food and Drug Administration. 2019. FSMA Final Ruse on Produce Safety [Online] [accessed 23 September 2019].
  6. SC Department of Health and Environmental Control. 2019. 2018 303(d) List of Impaired Waterbodies Methodology. Columbia, SC.

Originally published 10/19

If this document didn’t answer your questions, please contact HGIC at or 1-888-656-9988.

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