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Water Safety

When to Clean and Disinfect Your Cistern

​When do I need to clean my cistern?​

A cistern must be cleaned to remove sediment and any other contaminants. It’s a good idea to clean your cistern:

  • at least 1 time a year to remove sludge and sediment build-up, or more often if the water looks, smells, or tastes different
  • if contaminants (e.g., rodents, surface water from overland flooding) get in the cistern
  • after it’s installed and sediment needs to be removed from the bottom of the tank

​​When do I need to disinfect my cistern?

Whenever a cistern is cleaned, it needs to be disinfected .Your cistern needs to be disinfected without being cleaned if:

  • it’s just been installed, even if there is no sediment or contaminants at the bottom of the tank
  • you have plumbing maintenance work done from the inside of the tank (e.g., replacement of valves, pumps). Anyone who enters a cistern needs to wear clean footwear.
  • the source water that is delivered isn’t safe to drink (potable)
  • a bacteria test result comes back positive. If the source of bacteria isn’t easy to see, check the inside of the cistern.

Current as of: March 13, 2018

Author: Environmental Public Health, Alberta Health Services