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EPA Provides Information on Septic Systems: Special precautions and actions in aftermath of hurricanes

Release Date: 10/23/2005
Contact Information: For more information contact the Office of External Affairs at (214) 665-2200.

     Homeowners with septic systems need to take special precautions and actions in the aftermath of hurricanes.  What follows is a "how to" concerning the steps homeowners should take to ensure a safe return to normal septic system operation. Septic systems should not be used immediately after floods.

     Drain fields will not work until underground water has receded. Septic lines may have broken during the flood.

     If the ground area around your septic system is saturated, it is recommended that you do not pump the tank.  Pumping the tank would be only a temporary solution.  Under worst conditions, pumping it out could cause the tank to try to float out of the ground and may damage the inlet and outlet pipes. The best solution is to plug all drains in the basement and drastically reduce water use in the house.  

     Do not use the sewage system until water in the soil absorption field is lower than the water level around the house.

     Have your septic tank professionally inspected and serviced if you suspect 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. Contact your health department for a list of septic system contractors who work in your 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.

     Pump the septic system as soon as possible after the flood. Be sure to pump both the tank and lift station. This will remove silt and debris that may have washed into the system. Do not pump the tank during flooded or saturated drainfield conditions. At best, pumping the tank is only a temporary solution. Under worst conditions, pumping it out could cause the tank to try 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's manhole cover is secure and that inspection ports have not been blocked or damaged.

     Check the vegetation over your septic tank and soil absorption field. Repair erosion damage and sod or reseed areas as necessary to provide turf grass cover.

     Whenever the water table is high or your sewage system is threatened by flooding there is a risk that sewage will back up into your home. The only way to prevent this backup is to relieve pressure on the system by using it less.

     Here are some suggestions offered by experts for homeowners whose septic systems were flooded:

 * Use common sense. If possible, don't use the system if the soil is saturated and flooded. The wastewater will not be treated and will become a source of pollution. Conserve water as much as possible while the system restores itself and the water table fails.

 * Prevent silt from entering septic systems that have pump chambers. When the pump chambers are flooded, silt has a tendency to settle in the chambers and will clog the drainfield if it is not removed.

 * Do not open the septic tank for pumping while the soil is still saturated. Mud and silt may enter the tank and end up in the drainfield. Furthermore, pumping out a tank that is in saturated soil may cause it to "pop out" of the ground. (Likewise, recently installed systems may "pop out" of the ground more readily than older systems because the soil has not had enough time to settle and compact.)

 * Do not dig into the tank or drainfield area while the soil is still wet or flooded. Try to avoid any work on or around the disposal field with heavy machinery while the soil is still wet. These activities will ruin the soil conductivity.

     Flooding of the septic tank will have lifted the floating crust of fats and grease in the septic tank. Some of this scum may have floated and/or partially plugged the outlet tee. If the septic system backs up into the house check the tank first for outlet blockage. Clean up any floodwater in the house without dumping it into the sink or toilet and allow enough time for the water to recede. Floodwaters from the house that are passed through or pumped through the septic tank will cause higher flows through the system. This may cause solids to transfer from the septic tank to the drainfield and will cause clogging.

     Locate any electrical or mechanical devices the system may have that could be flooded to avoid contact with them until they are dry and clean.

     Aerobic plants, upflow filters, trickling filters, and other media filters have a tendency to clog due to mud and sediment. These systems will need to be washed and raked.

     For more information, contact the Louisiana Drinking water Program at 225-765-5038, http://www.oph.dhh.state.la.us, the National Groundwater Information Center at 1-800-551-7379, http://www.groundwatersystems.com/bioprimr.html, and the National Environmental Services Center at (800) 624-8301.  Contact your local health department for additional advice and assistance.