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What You Should Know About Flooded Septic Systems

A well-maintained and constructed septic system will better endure the stresses of heavy rains or flooding. Regular inspection is necessary to ensure proper functioning.

During heavy rains and floods, the ground can become saturated, preventing proper operation of the septic system. For example, a septic tank can collapse or float out of position.

Signs that a septic system is not working properly include the following:

  • Sink draining slowly
  • Toilet draining slowly
  • Floor drains overflowing
  • Sewage becomes visible outside the home especially over the top of septic systems

Before a Flood

To prepare your septic system before an emergency such as a flood, hurricane or earthquake:

  • Seal the access holes and/or inspection ports to keep excess water out of the septic tank
  • Be sure your septic tank is at least half full to prevent it from collapsing or floating
  • If your septic system requires electricity:
    • Turn off the pump at the circuit box before the area floods
    • Waterproof all electrical connections to avoid electrical shock or damage to wiring, pumps, and the electrical system

During a Flood

During an emergency such as a flood, reduce the amount of water used by limiting toilet flushing, dishwashing, washing clothes, and showering.

Severe flooding can put drinking water wells at increased risk for contamination from floodwater that may contain sewage. If your water well is submerged by floodwater or you detect a noticeable change in the water’s taste and appearance, then the well water should be boiled for at least one minute before using.

After a Flood

CAUTION: If your well was under water, do not drink well water until you know it is safe. Use a safe water supply like bottled or municipally-treated water, or boiled water. Be aware that floodwater may contain sewage. Have your well water tested. Renfrew County and District Health Unit offers a free private well water testing service.

If sewage has backed up into the basement, clean the area and disinfect surfaces in contact with floodwater. Use a chlorine solution of a half cup of chlorine bleach to four litres of water to disinfect the area thoroughly. Upholstery and hard-to-clean surfaces cannot be disinfected adequately and should be discarded or disinfected by a professional.

Precautions related to septic systems during and after a flood include:

  • Avoid contact with any septic system electrical devices until they are dry, clean and inspected for damage.
  • During flooded conditions, do not pump out the septic tank more than halfway or the tank may float out of the ground and damage the inlet and outlet fittings.
  • Septic tanks must only be pumped out by a licensed sewage hauler. Wastes cannot be discharged onto the surface of the ground or into watercourses.
  • Pump the septic tank as soon as possible.
  • Reduce all nonessential water use (for example, dishwashing, washing clothes, showering) until floodwater has disappeared over the sewage bed.
  • Flush toilets as little as possible or use a temporary toilet during a flood. Only begin re-using the septic system when floodwaters have receded below the level of the leaching bed.
  • Inspect the access covers to the septic tank to make sure they are not loose or damaged. Have your septic tank professionally inspected and serviced if you suspect damage. Signs of damage include settling or an inability to accept water.
  • Check the vegetation over your septic system. Repair erosion damage and sod or reseed areas as necessary to provide turf grass cover.
  • 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 waste water and lead to system failure.

More information can be found by contacting your local municipality or a septic specialist.

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