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Last modified: 24 Jan 2023 10:29am

septic tank

It’s important to remember that your septic tank is a living, breathing environment. To function effectively, it needs regular maintenance.

Before doing maintenance, check if you have a maintenance manual and know the system type and capacity of your septic tank. You can find this through building records held here at the Council or through the supplier.

Also check if there are any requirements around inspections or monitoring on the consent with Environment Canterbury before carrying out, or getting anyone else to carry out, maintenance.

  • 3–6 months: Check your disposal area. Inspect the ground for any changes or issues developing. There should not be any evidence of moisture on the ground surface.
  • 6 months: Check and clean outlet filters. This may be included in your service contract with your installer.
  • Annually: Inspect the tank for sludge and scum levels.
  • 3–5 years: Pump tank out. Or, do so if the top of the floating scum/solids is 75 mm or less from the bottom of the outlet or the sludge has built up to within 250 mm of the bottom of the outlet.

Systems with electrical float switches, pumps, or mechanical components should be inspected generally once a year.

The frequency of de-sludging depends on the age and capacity of the system, how many people use it and what goes into it (ideally only sewage and toilet paper, not solid items). Make sure you use appropriate chemicals at home to keep your septic system healthy. Most household cleaning products are fine, but it’s important to be moderate in your use. Household bleach can be used, but extra strong bleach should be avoided.

You may be able to do some maintenance yourself, but if a site investigation is needed, it is best to engage a drainage contractor or on-site wastewater servicing professional.

A professional check should include assessing sludge levels, checking pumps, pipework, tank inlets and outlets, cleaning as necessary, and flushing the irrigation area. You should also be provided with a maintenance certificate of work undertaken. Keep this certificate.

To find a wastewater servicing specialist, contact the Council, Environment Canterbury, septic tank pump out contractor, treatment plant supplier or plumbing/drainlaying company.