- Home
- Site Analysis
- Site Use
- Passive Design
- Water
- Minimising water use
- Stormwater controls
- Rainwater Systems
- On-site Wastewater Treatment
- Septic Tanks: Overview
- Septic Tanks: Design Checklist
- Aerated Wastewater Treatment Systems
- Disposal Systems
- Care and Maintenance
- Greywater: Uses and Safety
- Greywater: System Design and Installation
- Greywater: Gravity and Pumped Systems
- Greywater: Filtering and Treatment
- Greywater: Irrigation Systems
- Composting Toilet Systems
- Material Use
- Energy
- Health and Safety
- Other Resources
Water
Designing homes to use water efficiently, reduce costs and cope with more frequent droughts or storms.
Care and Maintenance
Well-designed, appropriately sited wastewater systems must be maintained to ensure they will work satisfactorily.
Contents of wastewater
To help the system work efficiently:
- specify water-efficient appliances
- warn the clients of the risks from overloading the system – this can be prevented by minimising water use, installing a separate greywater treatment system, and spreading heavy water-use activities (e.g. clothes washing) over several days
- advise clients against the use of strong chemicals as they will restrict the biological action within the tank – the client will have to select suitable household cleaning and washing products that do not hamper the decomposition process, and ensure that chemical products such as volatile thinners, bleaches and disinfectants don’t enter the system
- recommend that clients compost kitchen waste rather than fit a garbage disposal unit, as kitchen solids shouldn’t enter on-site wastewater treatment systems
- inform clients that systems cannot deal with condoms, dental floss, tampons, sanitary napkins, nappies and nappy wipes and these should be wrapped up and disposed of in the rubbish.
Maintenance programme
The owner should be provided with a programme of required maintenance. This programme will include regular inspection to check levels of sludge and scum in the tank. As a guide, the tank should be pumped by a specialist contractor when:
- the top of the floating scum is 75 mm or less from the bottom of the outlet
- sludge has built up to within 250 mm of the bottom of the outlet, typically at intervals between 3 to 5 years
- required by the manufacturer’s instructions.
For septic tanks, owners should be informed of the need to alternate flow to the disposal field at the distribution box at 3 to 6 month intervals.
For aerated plants in addition, the maintenance programme should provide for:
- the cleaning (usually 6 monthly) or replacement of filters as required by the manufacturer’s instructions
- monitoring of the effluent quality including pH level of the first chamber
- checking the submersible pump and float switch operation
- a record of all inspection maintenance and monitoring events
- switching between disposal fields for septic tanks
- replacement of the submersible pump at 7-10 yearly intervals.
For your clients
To help your clients understand onsite wastewater treatment options, safety issues, and the importance of maintenance, refer them to www.smarterhomes.org.nz/water/on-site-sewage-systems and www.smarterhomes.org.nz/water/re-using-greywater.