Septic tanks on school sites

If your school is putting in a septic tank, or upgrading your existing one, you need to think about what size you need and what your local council requires. You may need a resource consent. Septic tanks must be regularly maintained and cleaned.

Putting in septic tanks

A septic tank is a watertight tank, usually underground, that takes wastewater from toilets, sinks and basins. The septic tank contains bacteria that break down the wastewater and liquid effluent and then flows out into a soil disposal field.

If you’re putting in a septic tank or upgrading your existing one, think about these issues:

  • The septic tank should be large enough to hold all the waste generated in a 24-hour period, and the disposal field (the area that the waste flows into) should be big enough to cope with it. Your contractor can tell you what size you need.
  • The regional council may have its own requirements. In general:
    • water bores shouldn’t be drilled within 50m of a disposal field
    • the disposal field should be at least 20m away from streams, lakes and the groundwater table.
  • You cannot build on a disposal field or drive vehicles across it.

Resource consent

You may need a resource consent to discharge treated effluent to the disposal field. This is to prevent any adverse effect on the environment where there is a large number of people (60 or more) using the system.

Your local council will tell you if you need a resource consent.

Updating your resource consent

If your school roll increases, you may need a new resource consent or a variation to the old one. Talk to your local council about it.

Maintenance

Septic tanks are designed for a maximum daily sewage flow. Continually exceeding this will overload the system and cause it to fail, which could result in costly repairs or replacement.

To make sure your tank runs properly:

  • know your tank’s location and size
  • have it regularly inspected by a certified contractor
  • have it cleaned out every 2 years
  • keep records of all maintenance and set the date for the next inspection and clean
  • grow grass over the disposal field – not deep-rooting trees and shrubs
  • try to reduce the amount of wastewater, for example, install dual flushes and water-saving shower heads and quickly repair any leaks
  • keep toxic chemicals, like paints and oils, out of the system.

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