Grey water gardens

[Matt Trevatt]

I have seen some cool grey water and black water systems over the last few years. One system comprised of a 1000L water tank that had raw sewerage gravity fed into it. The overflow again gravity fed piped thru to a lined gravel bed that had the largest banana and papaya trees U have ever seen growing in soil beds above the gravel. This system was one of the many implemented in Ache.

Recently I read a book that diagrammed a grey water system in mexico that purified water thru a gravel and water plant bed. What struck me was how small the gravel bed was, at the most just 1.5 meters across. The water leaving the system was tested with less bacteria than the local drinking water.

[GaryD]

Hi Matt,

Can you remember enough of the detail in the book to be able to put a simple diagram together?

My favourite approach, so far, is the mini-wetlands idea described here.

Building a greywater treatment system is still on my TO DO list.

Gary

[Matt Trevatt]

The book is Oasis with Greywater.
Sorry a bit wrong on the size. It was 2meter D filled with 1/2inch gravel with 2 simple baffles to assist in circulation. Water plants being used to increase O2 in the water. Was being used for sceptic tank overflow! Not grey water.

[Bakes]

I'm putting in a treatment (similar to the Super Treat system but one tank not two) system in my new (yet to be built) house. All household wastewater flows to the tank where breakdown of material takes place it then goes into another chamber in the same tank where aeration converts it into biologically clean clear odour-free water. A touch of chlorine is added (very small amounts) before it is automatically irrigated onto the garden and/or lawn. I get two taps with the system and I can put them where I like. What I'm going to do with one is have a tap at the top of the property watering all my fruit trees (when they get planted) another tap I will hook up to some underground soaker hose and run this through my two small paddocks. I'm thinking that will keep me in green grass all year.

I'm also looking into some of these to save my water as I'll be on tank water only.
http://www.aquadivert.com.au/Homepage.php

[Cucuteni]

Hey folks,

Has anyone any experience/opinion on the feasibility of coupling a wicking bed and grey water system roughly like the simple small "living machines" of John Todd make? Seems one could route the water by gravity through a series of beds, or containters, which were on a downslope. This would both feed the veggies in the beds, clean up part of the nutrients and leave the exiting water cleaner than in would have been otherwise... (?)

Gary from Bellingham

[GaryD]

Hi Gary from Bellingham,

I'd advise strongly that you avoid the use of greywater on vegetables.

While there are some very effective strategies around for treating greywater (like mini-wetlands and the like) the chemicals that we typically use in a house (cleaners, deodorisers, insect sprays, etc) are the things that would scare me most about using greywater in this way.......far more so than any perceived threat from E-coli or other bugs.

Trees and fodder shrubs are as close as greywater gets to my food chain.

Gary (from Bundamba)

[Matt Trevatt]

Most grey water systems require a biological digestion process whether that is aerobic or anaerobic. A gravel bed before the wick beds would work.

[Coral Trout]

Gary (from Bundamba) has it. Don't use on things close to the ground - or leafy food. Just stick with the trees. Also Bakes, your system can be done. I have a header tank that fills over time and once full syphons out to drip irrigation. The syphon is created from the top of the tank with a flexible hose that hangs about 2/3 into the tank so I always have water at the tank and the line down the hill. As long as the irrigation flows out at a slower rate than the feed in (when it is filling) a syphon will start.

Also the diverter valve that is best is the Redwater Diverter not the Aquadivert as it hammers and will continue to flow if on solar hot water. www.redwater.net.au

[[bundle]]

GaryD & Matt Trevatt-

I disagree with your fear of growing food off of greywater.
If properly handled and applied greywater should be completely safe for all types of food production.

Obviously the use of cleaners needs to be regulated within such a system. Only quality organic, truly decomposing , low sodium soaps should be used. But harsh chemical cleaners, deodorizers, insect sprays and herbicides should be avoided and should be phased out regardless if you have a greywater garden or not.

We have learned to manage other animals feces into a source of nutrients, without concern of huge pandemics. There is no reason we can not and/or should not do the same with our own. We need to start turning out pollutant load into a stream of productivity.

Being concerned with the chemicals we introduce to our "waste" stream is missing the point. You are projecting the problems of chemical toxicity on to greywater.


And Matt...... You are correct in stating that greywater is treated anaerobicly/aerobicly. Lets expand on this a bit....sorry if you know this...info for others. First off, greywater's main pollutant load is in BOD5 (biological Oxygen Demand). This is the amount of oxygen required to break down the nutrients within the water. To clarify, the biological process will eat up the oxygen in the water, coming closer and closer to an anaerobic condition. Without enough oxygen, the greywater turns quickly from greywater to blackwater, loaded with bacteria and stench. For this reason greywater should never be held in a tank for more than 48 hours, or should be treated with an ATU (aerobic treatment unit).

The only reason anyone should ever hold greywater for an extended amount of time.....is if their hands are tied due to outdated On-site waste system requirements by the local jurisdictions. These regulations are developed by septic product suppliers and are NOT based on best practices or good science. Greywater is most misunderstood & misregulated "waste".

the irony is, that greywater is extremely easy to treat and use safely (in all climates).......the problem is no one stands to profit from landscape based solutions.

dan (bellingham)
[bundle]

[ande]

http://www.oasisdesign.net/greywater/index.htm
http://www.greywater.com/

I use it