Grey water irrigation would mean that the garden is watered through out the summer with water that would normally be wasted, reducing water use and waste water production
Greywater
Greywater is the waste water from showers, basins and sometimes washing machines. A greywater system recycles this water to another use within a house (rather than sending it to the sewer), typically for toilet flushing or irrigation.
System types
Most systems include a storage tank in which the greywater is held until it is required for use for toilet flushing and/or irrigation. To avoid build-up of harmful bacteria these tanks usually require the addition of Chlorine on a daily basis. There are also systems available that have no storage and filter the greywater before pumping it straight out to an sub-terraneous irrigation system. As there is no storage, there is no chance of bacteria growth within the water and therefore no treatment is required. The water is cleaned by the bacteria in the ground. With either system it is important to use only biodegradeable products in the house.
Our intension was to install a Water Lille System from Watersmart. This system collects the grey water from the house and sends this to the garden where it is distributed underground through a number of pods. To avoid over saturating the garden the moisture levels in the garden are measured, when moisture levels are exceeded the grey water is diverted directly to the sewer.
The Water Lille system sends grey water to the garden when moisture levels are below a set level
Different to Blackwater
Blackwater systems are also available in NZ. Blackwater is the waste water from the kitchen sink and toilets, although blackwater systems usually treat greywater as well. Probably the most common form of blackwater system in New Zealand is the septic tank. Wastewater enters a septic tank where some of the solids are digested by anaerobic bacteria and the remaining fluid drains off to the surrounding land. Newer blackwater system technology includes a second stage in the treatment process which helps the sludge break down further than in a septic system. Again the treated water that comes off from this type of system drain off into the surrounding land.
...Auckland Council will not approve grey water irrigation systems on small urban sites, but Kapiti Council requires them...
But not allowed by the Auckland Council?
All greywater and blackwater systems that are installed in Auckland must meet Auckland City's on-site waste water systems guidelines TP58. TP58 was written for black water systems with storage, which have in the past be used on large rural sites. The new grey water irrigaton systems take a different approach by not requiring storage and by only taking grey water are still required to be approved under TP58. As this standard does not consider these types non-storage greywater irrigation system, used on small city sites it is virtually impossible to consent them in Auckland even though they have been proved to be safe. We have still designed the wastewater system to allow for the separation of greywater and blackwater in the future when these types of systems are recognised by the Council. Interestingly Council's1 in other parts of New Zealand request the installation of these types of greywater systems in every new home.
"Kapiti Coast District Council has scored a first in the country by ensuring that all new housing developments will have greywater recycling measures in place to mitigate the water use issues that have plagued the district......1"
We would like to thank Steve at Watersmart for patiently working with us to try and get the Council to consent the grey water system. We haven't give up and will continue to work on getting Auckland Council to correct their outdated planning rules so that Auckland can benefit from the use of this system.
References:
- Local Government Magazine
- Kapiti Coast Council - "Grey water and your health"