This document has been jointly prepared by the Massachusetts Department of Public Health Division of Community Sanitation (DPH), and the Massachusetts Department of Environmental Protection (MassDEP) and is intended to provide guidance to the general public relative to managing pathogen risks from direct contact with floodwaters and/or sewage backups.
It is important to note that during and following flooding events, dangerous and even life-threatening hazards may exist, and the public is strongly urged to contact local and state emergency management officials for instructions on the procedures or actions necessary to safely avoid injury during these conditions.
This document is not intended to directly address these public safety issues (such as risks from accidental electrocution from flooded basements or downed power lines). Additional information on the public safety hazards associated with floodwaters can be found at the Massachusetts Department of Public Health , Red Cross and Federal Emergency Management Agency and Massachusetts Emergency Management Agency websites.
Pathogens are disease-causing agents, which can be in the form of bacteria, viruses, mold spores, or protozoans, and which are normally present in large numbers in sewage wastes. The nature and extent of potential pathogen risks of sewer backups and floodwaters will depend in large part on the potential contaminants expected to be in the waters. In general, the greater the extent of the sewage component, the more likely the potential for adverse impacts, and the more important the proper cleanup of the materials that have come into direct contact with the contaminated waters. The severity of the health threat therefore depends on the source of the water and the extent of penetration into the building environment. The extent of penetration is dependent on the porosity of contaminated materials, the quantity of floodwater, and the amount of time the water remains in contact with materials. Even floodwater or stormwater which has not been directly impacted by sewage discharges is likely to contain a wide variety of microbiological organisms (e.g., from animal wastes, street runoff, etc.) and must be properly managed. Some of these pathogens, such as mold spores, can even establish an ecological niche and present a health risk from chronic exposure for some time after the event. Preventive measures, and proper cleanup procedures are essential in mitigating the risk of infection; this guidance is intended to assist the public in these actions.
MassDEP and DPH recognize that flood conditions can occur in any watershed during severe wet weather events. The potential for, and extent of, flooding depends on many factors, including: topography, flood storage capacity, the extent and location of development, infrastructure constraints, and, of course, on the severity of the storm event. MassDEP, through implementation of its Combined Sewer Overflow Abatement program and Sanitary Sewer Overflow Abatement program, continues to require infrastructure improvements to mitigate the potential for untreated wastewater to be discharged during wet weather events. MassDEP also has implemented a Stormwater Policy which provides for performance measures to control stormwater pollution and peak flow rates for projects subject to the Wetlands Protection Act, Infiltration/Inflow Control Guidelines and Illicit Connection Initiative (sewers connected to separate stormdrain systems). While these programs are important in managing the risks from exposure to floodwaters, some risk will always remain, especially for low-lying properties during and following extreme storm events. As such, MassDEP has collaborated with DPH to develop guidance for the public who may be at risk to flood conditions. This Guidance includes suggested actions before and after flood events to minimize the public health risk and property damage. In all cases where flood conditions are expected or occur, the public should always remain in close contact with public safety officials as well.