The low down on septic tanks
THERE are specific rules governing septic tank installation and siting. 1. Modern pre-treatment systems
– A pre-treatment system is the first stage in handling household waste flows before discharge to land. Modern non-flush toilet systems for dwellings without water closets include:
VIP toilets (or ventilated improved pit toilets) Composting toilets Dehydrating toilets Non-flush toilet systems require a grey water septic tank and soak system to handle kitchen, bathroom and laundry waste water.
2. Modern pre-treatment systems for full waterborne wastewater servicing (flush toilet blackwater plus kitchen, bathroom and laundry flows) include:
Aerobic treatment plants (aerated systems and biofilter systems)
Advanced septic tank and sand filter (or fabric filter)
Advanced septic tanks (larger tanks with special effluent outlet filters in place of an outlet tee)
3. Modern landapplication systems
– A range of soil treatment systems is now available where trench systems are not suitable. These include: Dripline irrigation ETS beds (evapotranspiration-seepage)
LPED trenches (lowpressure-effluentdistribution)
Wisconsin Mounds for boggy areas or thin soils over rock or high groundwater.
ETS, LPED and mounds use the soil to treat advanced septic tank effluent in a far more effective way than traditional septic tank and trench systems.
Dripline systems disperse high quality treated wastewater into gardens where advantage can be taken of the effluent’s nutrient and water value. Usually the most environmentally effective on-site wastewater system comprises either an aerobic treatment plant or a sand filter plant, both of which produce high quality effluent for supporting plants in landscaped areas through dripline irrigation.
Septic tanks require ample topsoil and organic matter to enable bacteria to break down septic tank effluent and allow the water in the effluent to soak away effectively.
The soil provides the majority of the treatment in a septic tank and soak trench system.
Poor soils result in system failure.
The treatment process in an aerobic plant or sand filter system breaks down most of the waste matter and creates nutrients for plant growth.
The soil is the least important part of the treatment process but captures bacteria and viruses to allow them to die off with time. Engage a Designer – A designer will arrange an investigation of your site, its soil conditions and natural drainage patterns, and then discuss where you would like to put your dwelling and other on-site facilities.
Check with your council regarding designers operating in your area.
Applying for a building permit for your on-site system
– Your designer will also find out what your district council’s requirements are and check if your regional council has set any special environmental requirements for on-site systems in your area.
Using an alternative technology system
– If you decide to go with one of the alternative technology systems check with your designer as to its suitability for your site.
Make sure you ask about the system’s performance record and, if appropriate, ask the supplier or installer for a performance guarantee over the first three years of use.