Maintaining Your On-Site Wastewater Treatment System (includes septic tanks)

Septic tanks and on site waste water treatment systems need regular maintenance to work properly. You also minimise the impact on the environment if your system is well-maintained. 

Why regular maintenance?

Septic tanks and on site waste water treatment systems need regular maintenance to work properly. You also minimise the impact on the environment if your system is well-maintained.

There are health risks for you, your family and your community from poorly maintained waste water treatment systems. Poor maintenance of treatment systems can cause sewage effluent to rise to the surface or effluent to enter the groundwater system. People and animals can fall sick by coming into contact with raw sewage or by drinking groundwater which has been contaminated.

The life of your system depends on how much effluent is discharged each day and other factors like rainfall and general clogging of pores in the ground. But the greatest impact is how you maintain your system and what you put down it.

Components of system?

Your on site wastewater treatment system is divided into two parts:

• Wastewater Treatment Unit – generally a septic tank or aerated wastewater treatment system
• A Land Application System – generally field tiles, sand trenches, or low pressure sub-surface irrigation drip lines.

Both parts of the system need to be maintained to ensure that no health effects occur.

Do:

• Use biodegradable household cleaners and synthetic laundry powders or liquids (i.e. petroleum based)
• Use body washes and shower gels, instead of soap, as former are petroleum based
• Use the water and sud saver cycles on your dishwasher and washing machine (if fitted) and put a water saver device on your shower
• Fix any leaking taps or toilet cisterns
• Clean septic tank and filter when required
• Follow the maintenance and servicing requirements for your system
• Scrape all dishes to remove food material, etc before washing
• Keep all possible solids out of the system

Don’t:

• Use soap-based washing powders
• Install a waste master disposal in your sink
• Dispose of egg-shells, coffee grounds or tea bags as they are not biodegradable. Dispose of these in the rubbish and compost food scraps or put in rubbish.
• Dispose of strong bleaches, chlorine compounds, antiseptics or disinfectants, medicine or disposable nappies, sanitary napkins/pads or condoms into drains
• Allow fat to be poured down the sink
• Put petrol, oil, flammable/explosive substances, trade waste or chemicals down the drains
• Empty a spa or swimming pool into the system

Maintenance Guidelines

• Have your septic tank or wastewater treatment system pumped out every three to five years (depends on size of tank and how much material is going into it)
• Pump out tanks when the scum layer (layer of crust on top) comes down to within 100mm of the bottom of the tee junction or filter at outlet. Or when the sludge (build up of material on bottom of tank) and scum have accumulated to the extent that the scum and sludge take up 2/3 of volume of tank’s first chamber (check yearly)
• Check your filter regularly for blockage. Generally clean the filter when tanks is emptied (hose down with water back into the first chamber of septic tank).

Do I need a consent for my wastewater treatment system?

Most septic tanks or on site wastewater treatment systems installed prior to 1991 don’t require a resource consent. However, systems installed after this date will generally require both a building consent and a discharge consent, the former from your district or city council and the latter from Environment Canterbury. The consents will require that your system is well-built, complies with the treatment standard and is regularly maintained. See Environment Canterbury’s septic tank resource consent booklet for further details.

Change of ownership?

Your consent notice for your wastewater treatment system, its specifications and site plan must be kept in a handy and safe place. These are to be given to a new owner, if and when, a property changes ownership.

More Information

For more information about septic tank installation as it applies to the NRRP:

Read  What do I need to know to install a septic tank?  30kb