Greywater
Re-Use System

A Greywater Re-Use System is a grey water system designed to treat domestic wastewater excluding toilet waste. Councils are increasingly reluctant to allow homeowners to dispose of grey water without basic treatment. The days of being allowed to spray wastewater untreated onto the garden are over. Each State and Council have their own regulations and you will need to contact your local council to establish what they will permit alongside a waterless toilet. The following explains the situation primarily in NSW. Please note however that there are variations from State to State & from Council to Council.

Primary treated wastewater must be disposed of in sub-surface trenches, irrigation, or evapo-transpiration (ETA) beds. Septic tanks are the main example of systems that treat only to the primary level. Secondary treated water can be disposed of below ground, for example, by drip irrigation lines under mulch. Disinfected secondary treated water can be disposed of at ground level and in some cases by spraying in pre-designated areas. Aerated Water Treatment Systems (AWTS) treat to secondary level. Such systems include a disinfection unit, most commonly using chlorine. These systems typically cost around $8,000 plus in ground installation. There are then annual inspection and maintenance fees plus wear and tear on the pumps and aerators and electricity costs totalling some $800-1,000 or more per year.

In order to satisfy the Australian Standards (AS1547) requirements a grey water re-use system which cleans waste-water via a grease trap and gravity fed primary trteatment can be used. You can use the Greywater Re-Use System for disposal of the water via trenches, shallow sub-surface irrigation, or ETA beds. Suggest the Greywater Re-Use System to your geo-tech engineer and/or council.

Your council will probably ask you for a site plan. You may need to engage a Greywater Re-use Design consultant or geotechnical engineer to test your soil and produce a plan for distribution of the treated water. Make sure the consultant or engineer allows for the lower volume of water associated with a waterless toilet. This should result in an EDA (Effluent Dispersal Area) only 65% of the EDA for septic systems or AWTS  handling both black (toilet) and grey water.

We have found that some consultants & engineers have not had experience with composting toilets and so may not want to design a system around a waterless toilet. You should check before engaging anybody that they are happy to work with you in designing a system which is based on waterless toilets.

The Greywater Re-Use System is explained below.

The Greywater Re-Use System provides a simple and low cost effective means of treating grey water. Not only is the equipment low cost, but also, if your site is suitable, the only excavation work required to install the system will be the trenching. The ongoing costs will be less than those of a standard septic system.

The filtration tank, which is less than 1 cubic meter in size, consists of a pine bark coarse filter on top of a Bio-Mass filter. The coarse Pine Bark filter removes large particles & fats from the kitchen, and lint from the washing machine normally caught in a grease trap. Compost worms can be used in this layer. The filtered material and bark will compost over time and should be removed every 6-12 months and replaced with fresh bark, available form your local garden nursery. The pine bark is separated from the Bio-Mass by filter cloth. The Bio-Mass filter treats still finer materials, converting the organic content of the water into water soluble nutrients that can be used by your trees and plants. The final stage of primary treatment to is flowing over the bio-film on the 20mm aggregate at the base of the Greywater Re-Use System tank. If your distribution area is down hill from the filtration tank your engineer/consultant should be able to design a distribution system without the use of a pump. If this is not the case you will need a pump well.

The 120 litre pump well contains a submersible pump with float switch, capable of lifting water to a height of 5 metres. The tank, which measures 900mm in height and 600 wide, is located in the ground alongside the filtration tank. We can also provide an alarm system to alert you to a non functioning pump.

The Greywater Re-Use System is a Primary Treatment System and therefore you will need to distribute the treated water into a sub-surface irrigation trench system as specified by the Aust. Standard 1547. Make sure calculations of the EDA (Effluent Dispersal Area) size do not include an allowance for toilet water, which would make them unnecessarily large and

expensive. The following links to sample designs, NCG System and NCP System have been designed to AS1547-2000. Your plumber can lay the treated water application area (distribution system) in accordance with a design calculated to your particular situation  by Adobe Loos & Worms.

Adobe Loos & Worms can do this design for you and supply the major components for your system. Please contact us for more information.

The price of the Greywater Re-Use System Tank is $1660.00 with lid or $1,520 without lid.

The price of the Pump Well and pump is $1,024.00 plus freight. The pump is suitable for all situations with a head of water up to 5 metres. A High Level Water Alarm fitted is $420.

 GREYWATER RE-USE SYSTEM  Specifications

 FILTRATION TANK:

 ·         Material;                        Medium density grade polyethylene

 ·         Properties;  U.V stabilised, High stress resistance,
        High fracture resistance 

·         Thickness;                    Average 5 mm 

·         Construction; Rotational moulding, All surfaces are continuous with no welded or joined seams, Ribbed structure for additional strength 

·         Dimensions; 
Height 780 mm, Length 940-1025 mm, Width 820-910 mm 

PUMP WELL TANK: 

·         Material:                        Medium density grade polyethylene 

·         Properties;                     U.V stabilised, High stress resistance, High fracture resistance 

·         Thickness;                    Average 5 mm 

·         Construction;               Rotational moulding 

·         Dimensions;  Height 1200 mm, Diameter  1200 mm,

Schematic Diagram of Primary Filtration Tank

 
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Schematic & Image of Pump Well
 
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