Water NZ has helpfully shared some fantastic dos and don’ts around wastewater system use — we could be (happily!) doing ourselves out of a job here because many of the things listed below are the reasons we get called out to help with failures or emergencies! 

Have a read of the below and get in touch if you have any questions or concerns — we’re happy to share our knowledge.  

Do not overload the system.

• The system has been designed for a maximum daily wastewater volume. Ensure that this is not exceeded. 
• Avoid overloading the system with high short duration loads by spacing out water use as evenly as possible. For example: do not do all the washing on one day, and do not run the washing machine and dishwasher at the same time. 

Reduce solids input to the treatment unit by: 

• scraping all dishes to remove fats, grease, and so on before washing 
• keeping all possible solids out of the system 
• shake all the dirt and sand off your clothes before washing them 
• not using a food waste disposal unit (insinkerator) 
• not putting sanitary napkins and other hygiene products into the system

What can go down the drain: 

• all that has been first eaten by you 
• biodegradable soaps and low phosphorus detergents 
• septic-safe disinfectants, bleaches and toilet cleaners in small dilute amounts 
• washing machine and dishwasher wastewater
• shower and bath wastewater 
• toilet wastewater 
• milk and drinks

Minimise discharging the following substances: 

• some cold wash laundry agents are aggressively alkaline and can cause septic tank and treatment unit failure 
• bleaches, whiteners, nappy soakers, stain removers, disinfectants 
• sanitary pads, tampons, disposable nappies, condoms and excessive quantities of paper
• excessive fats, cooking oils and greases 
• antiseptics liquids. 
  

Do not discharge the following into the wastewater system: 

• DON’T USE flushable wipes. They can block the system 
• portable cassette toilet waste (use approved dump stations) • excessive volumes of bleaches and chlorine products 
• alkaline detergents such as caustic soda 
• acids, pesticides, herbicides, chemicals 
• paints, solvents, varnishes and paint thinners 
• antibiotics and medicines 
• drugs and pharmaceuticals 
• motor oil 
• toys, clothing, plastic bags and other non-biodegradable products 
• storm/roof water 
• pool or spa waste

To support the living ecology in the treatment tank and in the land application area: 

• use biodegradable soaps 
• use a low-phosphorus detergent 
• use a low-sodium detergent in dispersive soil areas 
• use detergents in the recommended quantities.

Got questions? Reach out to our friendly team — we’re happy to help! Contact Us