A septic system is an on-site wastewater treatment system used where there is no Council sewer connection, such as in rural areas. It treats and manages household wastewater using a septic tank and land-based disposal system.
Have a problem with your system?
If your toilet is blocked or your gully trap or septic tank is overflowing, contact a registered drainlayer.
A drainlayer will identify the issue and may arrange for a septic tank contractor to pump out the tank if needed.
Important - If groundwater levels are high, often in winter, talk to a drainlayer before pumping your tank out. In some cases, an empty tank can lift out of the ground.
If you need a new system or want to upgrade an existing system, contact a wastewater site assessor to discuss suitable options.
See our list of Wastewater site assessors
If you’re unsure, our staff can also provide advice.
What is a home wastewater system?
A home wastewater system collects, treats and disposes of wastewater from your property.
Wastewater from your kitchen, bathroom, laundry and toilet flows into a tank where solids and liquids are separated and treated.
The treated liquid (effluent) is then disposed into the soils. When systems are well maintained and operating correctly, they pose minimal risk to health and the environment.
Guides
For detailed information on installing, managing and maintaining a septic system, see our residential wastewater systems page and the related guides below.
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Consents and upgrades
You may need to upgrade or replace your system if:
- It's not functioning properly
- it regularly overflows
- the soakage or disposal area has failed.
You will need a building consent if:
- you are building a new home
- you are renovating or extending and upgrades to your system are required.
You may also need a resource consent, depending on:
- the type of system
- property size
- location such as coastal or sensitive areas.
If you're buying a property, check with us if there are any consent conditions or maintenance requirements.
Renting a property with a septic system
If you rent a home with a home wastewater system:
- use detergents and cleaners that are labelled septic-safe
- do not dispose of fats, sanitary products, chemicals or paint into the system
- avoid excessive daily water use.
Check with your landlord to confirm responsibility for:
- tank pump-outs
- repairs
- regular servicing (for advanced treatment systems).
What not to put down your drains
Certain products can damage your septic system by killing the beneficial bacteria that break down waste. This can lead to bad odours, blockages and system failure.
Don't put the following down any drain or toilet (inside or outside):
- nappy soakers and sanitisers
- bleach and fabric whiteners
- disinfectants
- high-strength ammonia cleaners
- stain removers
- bulky laundry powders with fillers
- excess grease, cooking oil and fats
- paints, varnishes, thinners, petrol and machine oils
- caustic or acidic drain-cleaning products
- unused or expired antibiotics and strong medicines
- swimming or spa pool backwash water
Avoid putting solids into your system
Items that don’t break down easily can build up in your tank and cause blockages or reduce system performance.
Do not flush or dispose of:
- sanitary pads and tampons
- disposable nappies
- tissues
- condoms
- food waste from garbage grinders
- coffee grounds
Safer cleaning options
Where possible, use cleaning products that are septic-safe and biodegradable.
Safer alternatives include:
- soap
- shampoo and conditioner
- Lux flakes or similar soap-based cleaners
- concentrated laundry powders (labelled septic-safe)
- liquid laundry detergents
Simple household cleaning options:
Baking soda
- use on a damp sponge for general cleaning, or
- mix 4 tablespoons in 1 litre of warm water for toilet cleaning.
White vinegar
- mix 2 tablespoons in 1 litre of water
- use in a spray bottle for windows and surfaces.
Borax
- mix ½ cup in 4 litres of water as a disinfectant
- available from pharmacies.
Using the right products helps keep your wastewater system working effectively and extends its lifespan.