This being an old thread, I post the following as general information keeping in with the poster's questions.
As already posted, grey water treatment systems cost a lot of money, are rarely considered for residential households and treated greywater will still retain high salt levels.
The commonly advertised domestic units are mostly diversion systems that distribute untreated greywater to the garden, mainly through fixed drip lines. Many people think that these common systems treat the greywater but THEY DO NOT!
There is a lot of data available that shows that overuse of greywater can have a detrimental effect on the soil and beneficial microbes. Turf has greater long term resilience but should still not be over-watered with grey water.
The ATA's Renew magazine Issue 112, pages 69-70, has an article about garden greywater use and its effect on soil sodicity and other findings.
A washine machine's final rinse is relatively clean and this can be used by fitting a diverter valve into the laundry drain pipe. This is cheap and effective.
There are many weather data collection stations throughout Australia. The below link allows people to access information including each month's and year's rainfall data, simply find the station number nearest you, enter it where required, then click! This will allow a reasonably accurate calculation of your district's rain pattern.
This is important information if considering harvesting rainwater but do not expect to collect the entire amount of rain that falls on your roof 'catchment' area. Evaporation alone could account for an initial .5 to 1 mm loss. Also be aware that downpipes do not always harvest equal roof areas. Also consider the direction that most of the weather comes from. If there is a large tree that puts a roof area in a rain shadow, yield will be poor. If possible, harvest roof areas that gain most benefit from the direction of the prevailing weather.
Re getting quotes; this is the hard part and there are few experts. To save BIG money when installing tanks, householders need to take charge and avoid going in like lambs to the slaughter.
Things you can do:
Lay the tank and pump base yourself or ask a friend to help. If concreting, don't forget the Reo!
Have the outside power point already fitted. When you use your own electrician, you can pre book him to do other jobs while he is there.
Have the tank and pump in place before the plumber arrives.
Do your homework and buy the tank and pump (with a large pressure tank) yourself. Carefully consider the position, height and size of all tank fittings.
Check these forums for other advice.
Posted Saturday 7 Aug 2010 @ 7:11:28 am from IP #