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Preventing Water Damage from Sanitary Sewer and Storm Drain Backup


Sanitary sewer and storm drain backup can damage building foundations, walls, floor coverings, appliances and equipment.

Additionally, raw sewage is a big health hazard. Sewage water may contain a lot of contaminants and hazardous materials, including bacteria, viruses, pesticides, fungus and microorganisms — all things you don’t want in your building. It’s also extremely costly to clean up, and during the cleanup and repair period, you won’t be able to use your building for an extended amount of time.

Fortunately, some minor maintenance and good hygiene practices will minimize the risk of sanitary sewer and storm drain backup. Take the following precautions to prevent water damage to your building:

Sanitary Sewer Maintenance

  • Do not dispose of grease through the sink or toilets. Warm grease will go down the sink and then solidify when it cools to form a hard blockage. By draining grease in a separate container (empty cans work well) instead of the sink, you minimize the risk of a backup. It may be helpful to harden the grease in the freezer before disposing of it.
  • Use strainers in sinks to catch food scraps, then be sure to dispose of the food scraps in the garbage. Food particles and coffee grounds build up in the sewer trap and create a blockage. Some grains, like rice, will swell up in water and accelerate this process.
  • Do not flush solid waste down the toilet. This includes disposable diapers, personal hygiene products and wet wipes (regardless of what the package says, wet wipes are not flushable). Toilets are designed to eliminate liquid waste. Attempting to flush anything other than toilet paper is a quick route to major sewer problems. Provide convenient receptacles for personal hygiene products and other waste to keep it out of your sewer system.
  • Never connect floor drains, drain tile, downspouts or sump pumps to the sewer line. Such connections may cause sewage to back up into the building.
  • One of the common causes of sewer line backups is tree root damage. Do not plant deep-rooted landscaping on top of or next to the sewer laterals (the connection between your building and the public sewer line). If the roots penetrate the sewer line, they can restrict or even block the sewer line. Map your sewer lines and trim tree roots to minimize the risk of damage. Replace any damaged line before a blockage occurs.
  • If your sewer system doesn’t have a cleanout, have one installed to allow access to clear any blockage in the line. Easy access to a cleanout can change a sewer blockage from a major shutdown to a minor inconvenience.

Storm Drain Maintenance

  • Recycle yard waste. Raking or blowing leaves, grass clippings and small tree limbs into the street allows this material to enter storm sewers, which can cause them to back up.
  • Install a sump pump. Sump pumps will remove water from the building’s foundation drain tile through a discharge tube outside of the building.
    • Hire a qualified plumbing contractor to install the sump pump.
    • Consider a backup. Because severe storms may result in power failure, a battery-powered backup sump pump is highly recommended.
  • Install a backflow prevention device, which will prevent raw sewage from an overloaded main sewer line from backing into the building’s drainage system.
    • Hire a qualified plumber to install the device according to local building codes.

Basement Maintenance

  • Keep valuable items on shelves and off the floor to prevent damage to valuable interior contents.
  • Better yet, keep important documents, valuables and hard-to-replace items out of the basement.
  • Consider installing flooring that is not susceptible to water damage, such as ceramic tile.
  • If you have an exterior basement stairwell, make sure the door is adequately caulked and weather-stripped to prevent water from penetrating. (This is a prime area for water to accumulate from surface runoff from heavy rains.)

Not only is damage from storm and sanitary sewer backup costly to clean up, but it can have a long-term effect on your operations, depending on where the damage has occurred in your building. To prevent this from happening, it is important to follow these recommended precautions and do routine checks at least twice a year to look for things that could cause a backup to occur.

© 2024 GuideOne Insurance. GuideOne® is the registered trademark of the GuideOne Insurance Company. All rights reserved. This material is for informational purposes only. It is not intended to give specific legal or risk management advice, nor are any suggested checklists or action plans intended to include or address all possible risk management exposures or solutions. You are encouraged to retain your own expert consultants and legal advisors in order to develop a risk management plan specific to your own activities.