Thread: Grey Water Tank

Originally Posted by silentC

Edit: The Bogle/Chandler Case

So if you are going to check out your grey water tank and havnt emptied it for a couple of days, make sure you put some clothes on

ok just been reading some of these posts and wondering if u can store the grey water for 24 hrs could u rig up a small pump to pump the greywater (thru a filter ) back into the toilet system so u are flushing with used water ?

Thought of a 200 lt tank with a float value in it so always some water there (mains ) but then collecting the shower washer water as well and reusing that then being able to perhaps pump the water out onto the garden as well if the tank was filled ? would this be legal ?? as this would be diluted grey water would that reduce the toxicity of the water / gases

Dzcook,

You can download the water recycling regulations (pdf) from the epa website, or PM me your email address if you'd like me to email them to you.


joez71

You have to keep in mind a couple of things:

You don't want any risk of cross contamination from your grey water to your water mains. You have to be very careful about how you do it. Just sticking a normal float valve in is probably not going to be good enough.

Also, the water that you put into your cisterns will sit in the cistern and the pan for any length of time. Say you flush your loo just before you go on 3 weeks holiday. It's going to be pretty rank by the time you get home.

Thanks for these posts folks; read with interest.

I was thinking about installing a rainwater tank for the garden watering (living in the 'urbs) and wondered where I could find out the formula to match the tank size to the roof collection area. Any advice?

Course at the moment a small bucket would do but we live in hope.

Thanks to the metric system it's easy.

For every square metre of roof space and every metre of rain you'll get 1000 litres of water.

So if your house is 20x10 metres you'll have a roof area of 200 square metres. Average annual rainfall for Melbourne is 600mm so you'll have 200 * 600 = 120,000 litres of water a year.

You could put a pretty big tank on your house say 45,000 litres but you'll need a big backyard to have the space for it.

How big an area do you have for a tank?

Originally Posted by dzcook

ok just been reading some of these posts and wondering if u can store the grey water for 24 hrs could u rig up a small pump to pump the greywater (thru a filter ) back into the toilet system so u are flushing with used water ?

Thought of a 200 lt tank with a float value in it so always some water there (mains ) but then collecting the shower washer water as well and reusing that then being able to perhaps pump the water out onto the garden as well if the tank was filled ? would this be legal ?? as this would be diluted grey water would that reduce the toxicity of the water / gases

Yes you can, but definitely check some sites about how to do it properly. A filter is not enough - you will need to also give the water an actual treatment process. There are a few different ways of doing it. The one that we were using on the ANZACs involved putting salt into the water (when salt water was being used in the system, this obviously wasn't a problem, but if the ship was being used in a fresh water environment, then we'd have to supply the salt!). This is then passed through a catalytic cell which basically zapped the water with electricity between 2 grids. This killed some of the bugs, and the rest, well, the electricity also split the salt into sodium and 'ta da' chlorine. It would then sit in a tank for a predetermined amount of time for the chlorine to do its job, then the whole lot was pumped overboard.

Not sure what process is used for residential grey water systems, but it is more than just a filter - thus the cost.

Originally Posted by rsser

Thanks for these posts folks; read with interest.

I was thinking about installing a rainwater tank for the garden watering (living in the 'urbs) and wondered where I could find out the formula to match the tank size to the roof collection area. Any advice?

Course at the moment a small bucket would do but we live in hope.

Easy enough to do yourself - calculate the roof area, then multiply it by the average rainfall that you expect to receive and want to capture completely (eg roof area = 150 m^2 rainfall = 5mm, so a tank to capture it all would be 0.75m^2. ie 750l )

See - even a small amount of rain will fill one of those 1000l tanks very easily. Imagine what a decent rainfall would supply!

Grunt sweeps in, beats me to the post again

I knew I shouldn't have replied to 2 posts at once!

Thanks guys; this forum really hums!

I want to fill off the garage, which is around 10 x 5 m, so your formulae gives 30k l in an average year - assuming we have any more of those. There's space behind the garage at the top of the block slope for a tank.

I read in the paper that a 1k l tank would give you 60 mins of hosing (not sure whether that was by pump or gravity feed) - all we have is a small veggie patch and a few trees and shrubs so maybe 30k l would be overkill. What do you think?

There are some handy calculators here : http://www.polyworld.com.au/calculations.htm


joez

I'd go with 2000L - it is only about $150 more than the 1000, so it really isn't that much more for double the capacity.

Thanks again; v. helpful.

Yes, forgot to mention there's space but very limited access to get the tank up the back so it may need a rectangular job or several in series.

oh and dont go to Bunnies or some such place to purchase your tank. Grab the Weekly Times (comes out on Wednesdays) and sometimes the trading post and you'll find all the manufacturers sales advertisements listed together. When choosing a tank, go for the biggest you can afford and fit.

sf

You can also try ebay.

These sort of tanks might be just the thing.


Also, getting hold of a tank at the moment might be a bit tricky. Up to 4 months waiting period for some tanks. I ordered a 25,000 litre tank in November which I won't get until Feb.