Floods and Sewage Spills

Natural disasters often lead to microbial contaminations such as indoor mold growth and contamination through flooding event that leave sewage and other hazardous material behind. This can negatively affect the drinking water supply and contaminate or destroy living spaces.

Should I Test for Sewage Contamination?

Microbiological contamination of water is responsible for numerous outbreaks of gastrointestinal illnesses that occur every year in the United States. Most of these outbreaks are a result of sewage contamination. Living spaces can be contaminated with sewage or wastewater through a variety of sources, including raw sewage overflows, severe flooding and leaking sewer lines or septic tanks. Exposure to sewage increases the risk of contracting gastrointestinal and other related illnesses. If you suspect that a source of water might be from a leaking sewer line or if you want to determine the amount of contamination from a backed up toilet, drain or other water source, then testing for sewage contamination may be helpful.

How do I Test for Contamination?

Testing for sewage contamination generally involves analysis for organisms that are called “indicators.” These organisms are considered indicators because they are unique to sewage or, more specifically, fecal contamination where they are found in high numbers. Historically, a number of organisms have been used as indicators and are included in categories such as Total Coliforms
and the misnomers Fecal Coliforms and Fecal Streptococci. However, many of these have fallen out of favor because they can also be found naturally in the environment. These organisms, the most widely used indicators for fecal contamination, are E. coli and members of the genus Enterococci, because they exist in high numbers in the lower intestines of warm-blooded animals.

What do the Results Mean?

Bacteriological tests look for the presence of E. coli and members of the Enterococcus group (E. faecalis, E. faecium, E. gallinarum and E. avium) that specifically indicate contamination with sewage. The presence of members within the Enterococcus group in the sample tested may indicate the fecal contamination. Coliform bacteria occur naturally in soil and in the intestines of humans and animals. E. coli is one kind of fecal coliform that is common in the intestines of humans and animals. The presence of E. coli in the sample tested verifies fecal contamination. The majority of E. coli types do not cause human illness. Shiga-toxin producing E. coli including O157:H7 is one specific subset of E. coli that can cause serious illnesses.

What if I have a Private Sewage System?

When flooding or saturated soil conditions persist a private sewage system cannot function properly. Soil treatment systems for wastewater rely on aerobic regions (with oxygen) to reduce the amounts of chemicals and living organisms (viruses, bacteria and protozoa). When the soil is saturated or flooded, those hazardous materials can enter the groundwater and your drinking water supply.