By Todd Layt
We cannot wait for governments to provide us with water for gardens, so the best thing to do is organise our own supply. This can be achieved through water tanks, or even better, grey water systems. Water tanks are easily found, and information is widely available. The main thing to consider is that small tanks don’t offer a good long term solution. Put in larger tanks, as water in smaller tanks can be quickly used up in times of drought. There are now some good sized tanks that come in many shapes and sizes, there are some that are thin and narrow, some that fit under the house and stylish tanks that become part of the landscape. Any tank less than 4,000 litres is a little small to provide a good back up water supply. If space is limited, install a few smaller tanks in sequence to make up the volume needed.
The information available on grey water systems is a lot more confusing, so I have tried to gather information on 3 good systems that seem to work and are easy to organise to be installed. If possible, forget the small installations that just divert water from washing machines, as the amount of water is so negligible. Only about 50% of existing homes can have storage grey water systems installed, so if feasible, it is better to do it at the time of building.
Basically, houses on stumps, or a reasonable amount of two storey houses on slabs, can have their waste water split into grey water (from showers, taps, and laundry other than kitchen waste or toilets), and black water (from kitchen waste and toilets). The black water is sent down the sewerage, and the grey water is recycled and stored with these systems. I would suggest only using systems that produce class A or class A+ water, so that storage is allowed.
Water storage is essential if a long term solution to water restriction is to be found. Two good grey water recycling systems that use biological processes are the Nubian (www.nubian.com.au) and AquaReviva sytems (www.newwater.com.au). Both can clean and store up to 1,500 litres of water per day, although most families only make about 500 litres of grey water in a day. Systems like these cost about $10,000 or more. A lot of money, but this could be a gardeners ticket to freedom from water restrictions.
Older single story houses on concrete slabs can rarely be split into the 2 water categories needed for grey water recycling. This is where the recent invention of the Econova (www.econova.com.au) comes in. This system recycles both black and grey water into A+ class water good enough to drink. However, as usual, our governments are moving slowly on this issue. In non-sewered areas, this system is allowed for black water recycling in Queensland and NSW, but nowhere has it been approved for use in sewered areas. So our governments say "you cannot water your gardens with our water, and only about half of homes can, in practical terms, recycle their waste water". Typical bureaucracy! I know this technology has only been available since November 2006, but time is of the essence here. It is time governments got a move on. Apparently Victoria and South Australia are looking at it at the moment.
Now that your landscape has guaranteed access to water through a non-government water supply, you can consider your landscape. Firstly, for a choice between using a lawn or garden. The truth is that many native gardens use about the same water as lawns. The University of Western Sydney published a study which showed primarily native gardens used 4.7 kL of water/100m2/month, whilst warm season turf such as Kikuyu, Buffalo grass, and Couch used 4.3 kL of water/100m2/month. Primarily, exotic gardens used 8.7 kL of water/100m2/month; approximately twice as much as lawns and native gardens.
Lawns such as Palmetto Buffalo or Empire Turf can be extremely drought tolerant compared to water hungry lawns such as Fescue and Rye Grass. Native Dianellas like Little Rev, Little Jess, Tasred and Cassa Blue, and Lomandras such as Tanika and Nyalla are so tough, that in the eastern states they thrive on no irrigation at all. If you want more water hungry plants, keep them to one small area of the garden so as to not waste a lot of water.
Mulch is another great water saving device, but beware, some mulches will actually reduce the amount of water available for plants. Basically, good chunky mulches, with no or very small amounts of fine particles help retain water and work well. Mulch with a high proportion of fine grade material have in research sponsored by Yates, shown that they can actually repel water, making a garden dryer.
Shade around a garden can reduce evaporation. This can be either from a few well placed trees, or a garden that is densely planted with few gaps. The vegetation covered areas will be cooler and allow for much slower drying out of the soil, especially if the right plants are used. Having fewer gravel or concrete areas and more greenery will also keep landscaped areas cooler, again reducing garden dry out.