What’s a Holding Tank?

A holding tank is a single compartment tank and doesn’t have a divider. Everything that goes down the drain ends up in the holding tank and it stays there until it is pumped out. Holding tanks will need to be pumped out every 6 to 8 weeks but maybe sooner depending on the size of the tank and the usage amount. It is commonly used at cottages where it is not being used that often and therefore it does not need to be pumped that often, maybe only 1 to 2 times a year. An alarm is normally installed inside the tank so you can get it pumped out in time so it does not backflow into your house. Holding tanks are generally cheaper to install because you do not need a septic field. They are installed outside underground. They normally last many decades. If you are wondering if you can install one you would have to check with your local jurisdiction. 


  • Do make a permanent record of where the key parts of your system are located for future maintenance, such as tank pump outs or repairs.
  • Do have your Holding tank pumped out regularly.
  • Do keep records of pump outs and maintenance.
  • Do use water conserving devices where possible. Low flush toilets and shower heads are commonly available.
  • Do have manually cleaned lint traps on your automatic washer.
  • Do check any pumps, siphons, or other moving parts of the system regularly.
  • Do remove or prevent trees with large root systems growing near the Holding Tank.
  • Do check your interceptor drain regularly to ensure that it is free flowing.
  • Do compost your kitchen waste.
  • Do increase the size of your Holding tank, and have it pumped more often, if a garbage grinder is to be installed.


  • Don’t overload the system with high volumes of water.
  • Don’t connect basement sump pumps to the on-site system.
  • Don’t connect backwash from water treatment devices directly to the on-site system.
  • Don’t allow large amounts of fats, chemicals, or solvents to enter the system; don’t allow any plastics to enter.
  • Don’t enter a Holding tank without proper ventilation, a second person (adult) above ground, and other requirements for confined spaces apply. Sewer gases can be fatal.
  • Don’t cover the tank with asphalt or concrete or other impermeable material.
  • Don’t put in a separate pipe to carry wash waters to a side ditch or woods. This ‘greywater’ also contains disease carrying organisms.
  • Don’t wait for signs of failure. Check the system regularly.

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