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ACT 537: What To Do With Your Septic System After A Flood

What should you do after the floodwaters have receded?

  • Do not drink well water until it is tested. Contact the local health department.
  • Do not use the on-lot sewage system until water in the soil absorption field is lower than the water level around the house.
  • Have the septic tank professionally inspected and serviced if there is suspected damage. Signs of damage include settling or an inability to accept water. Most septic tanks are not damaged by flooding since they are below ground and completely covered. However, septic tanks and pump chambers can fill with silt and debris and must be professionally cleaned. If the soil absorption field is clogged with silt, a new system may have to be installed.
  • Only trained specialists should clean or repair septic tanks because tanks may contain dangerous gases. Check the local phone book for a list of septic system contractors who work in the area.
  • If sewage has backed up into the basement, clean the area and disinfect the floor. Use a chlorine solution of a half cup of chlorine bleach to each gallon of water to disinfect the area thoroughly.
  • Have the septic system pumped by a qualified contractor as soon as possible after the flood. Be sure that both the septic tank and pump tank are pumped. This will remove silt and debris that may have washed into the system. Remember: The tank should not be pumped during flooded or saturated drainfield conditions. Under worst conditions, pumping it out could cause the tank to float out of the ground and may damage the inlet and outlet pipes.
  • Do not compact the soil over the soil absorption field by driving or operating equipment in the area. Saturated soil is especially susceptible to compaction, which can reduce the soil absorption field’s ability to treat wastewater and lead to system failure.
  • Examine all electrical connections for damage before restoring electricity.
  • Be sure the septic tank cover is secure and that inspection ports have not been blocked or damaged.
  • Check the vegetation over the septic tank and soil absorption field. Repair erosion damage and sod or reseed areas as necessary to provide turf grass cover.

How can you prevent sewage from backing up into your home?

  • Plug all drains in the basement and drastically reduce water use in the home.
  • Do not use the system if the soil is saturated and flooded. Conserve water as much as possible.
  • Septic systems with pump chambers can be clogged by silt during times of flooding; take measures to prevent any silt from entering the system.
  • Do not open the septic tank for pumping while the soil is saturated; this can lead to silt entering the drainfield.
  • Avoid any work on or around the disposal field while the soil is still wet or flooded to prevent ruining the soil conductivity.
  • If the septic system backs up into the house, check the tank for outlet blockage as flooding will cause fats and grease in the tank to float and potentially clog the outlet tee.
  • Ensure any electrical or mechanical devices in the system avoid contact with the flooded system until it is dry and clean.
  • Mud and sediment have a tendency to clog filters and aerobic units during a flooding event; these systems will need to be washed and raked to prevent clogging.

You should also contact the local municipality or Sewage Enforcement Officer for additional advice and assistance.

For more information on onsite/decentralized wastewater systems, call the National Environmental Services Center at 304-293-4191 or visit their website.

Adapted from a U.S. Environmental Protection Agency Publication, “Septic Systems—What to Do after the Flood.”

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