Fecal coliforms are bacteria found in the digestive tracts of warm-blooded animals, including humans, and their waste. Detecting these bacteria in water indicates fecal contamination. Monitoring fecal coliform levels assesses water quality and identifies potential public health risks.
Understanding Fecal Coliform
Fecal coliform bacteria are a subgroup within the larger coliform group. While many coliforms exist naturally in soil and vegetation, fecal coliforms specifically originate from the intestines of warm-blooded animals. Most types are not directly harmful to humans; instead, their importance lies in their role as indicators. If fecal coliforms are present, it suggests that other disease-causing microorganisms (bacteria, viruses, or parasites) shed in feces might also be present.
A well-known example is Escherichia coli (E. coli). While many strains of E. coli are harmless, certain types can cause severe illness. E. coli is often monitored more closely because its presence strongly indicates recent fecal contamination.
Sources of Fecal Coliform
Fecal coliforms enter the environment primarily through human and animal waste. Significant sources include human waste from failing sewage systems, leaking sewer pipes, or inadequate wastewater treatment plant discharges. Septic tank failures can also release contaminated water into groundwater and surface water bodies.
Animal waste contributes substantially to environmental fecal coliform levels. Runoff from agricultural lands, containing livestock manure, can carry these bacteria into streams and rivers. Urban areas also contribute through unmanaged pet waste, which rain can wash into storm drains and local waterways. Wild animals can also deposit fecal matter directly into natural water sources, especially during heavy rainfall.
Health and Environmental Implications
Elevated fecal coliform levels indicate potential waterborne pathogens that can cause health problems. Contact with or consumption of contaminated water can lead to gastrointestinal illnesses, including nausea, vomiting, diarrhea, and abdominal cramps. Other possible health effects include skin rashes, eye infections, and respiratory issues. Individuals with compromised immune systems, young children, and the elderly are particularly susceptible.
High fecal coliform levels also affect aquatic ecosystems. Increased bacterial loads deplete oxygen as bacteria decompose organic matter, harming aquatic organisms. Contaminated water can impact recreational activities, making swimming, fishing, and boating unsafe. Public health advisories or beach closures may be issued to prevent exposure and limit access to natural resources.
Testing and Safety Guidelines
Detecting fecal coliform in water involves laboratory methods like membrane filtration or multiple-tube fermentation. These tests quantify bacteria in a water sample, expressed as colony-forming units (CFU/100 mL) or most probable number (MPN/100 mL). The results are then compared against established safety standards.
Safety guidelines for fecal coliform vary depending on the water’s intended use. Drinking water standards require the absence of fecal coliforms. Recreational waters, such as those for swimming, have higher permissible limits; for example, 200 CFU/100 mL is a common threshold, with higher levels prompting advisories or closures. When fecal coliform levels exceed these limits, public health authorities may issue advisories (e.g., boil water notices) or close recreational areas. Actions include identifying contamination sources and implementing remediation to restore water quality.