Pathogens in Stormwater FAQs
Pathogens are microorganisms that can cause diseases in other life forms. Pathogens can include bacteria, fungi, and viruses, found commonly in sewage, hospital waste, run-off water from farms, and in water used for swimming. Most pathogens are parasitic, living off a host, and cause diseases indirectly by obtaining food from, or shelter in, the host.
Pathogens can enter stormwater runoff through combined sanitary/stormwater sewer overflows the improper disposal of pet waste[iii], and soil contaminated with solid waste.[iv] A large variety of microbes are found in stormwater, however, the disease-causing microbes (pathogens) are the primary concern for stormwater runoff.
Pathogens are considered biological hazards that produce disease, therefore the removal of pathogens in waterways, especially through stormwater discharge systems is essential. Pathogens in water sources can have serious, negative, health impacts on people with compromised immune systems and on certain species of fish and wildlife.
The bacteria species E. coli and fecal coliform are used in water quality analysis as indicator species. Fecal coliform and most forms of E. coli are harmless, but their presence indicates possible fecal material contamination and the presence of other harmful microbes.[v] Two common pathogens found in stormwater are Giardia and Cryptosporidium[vi] which cause two of the most common waterborne diseases in the U.S that can lead to symptoms such as headaches and gastrointestinal illness. [i] Both can persist in the environment for months and are highly resistant to disinfection.[vi][vii][viii]
Young children and people with compromised immune systems may be particularly at risk from these microbes. E. coli 0157:H7 can cause more serious effects including kidney failure.[ii] Certain species of fish and wildlife are unaffected by the microbes commonly found in stormwater while other species experience symptoms similar to those experienced by humans.