Using water in the garden
It is only common sense to avoid using treated drinking quality water for the garden.
Whether you are washing cars on the drive or watering your vegetable patch there are alternatives to using tap water.
Rain water
This can either be collected in butts for use with a bucket or watering can or stored in large tanks and pumped for all types of non potable uses. See Rainwater recycling
Grey water
This can be collected from the output of handbasins, showers, baths, and washing machines and once filtered can be used for irrigation (even on plants intended for food use although they should be washed in clean water before consumption and you wont waste this water because it can go back on the garden!) See Greywater recycling
Black water
Although some systems are available to treat it for irrigation use and some might suggest it
WE WOULD NOT RECOMMEND THE USE OF BLACKWATER FOR ANY PURPOSE
There are other ways that you can reduce the amount of treated water used in the garden
Consider your hard landscaping; make sure that when it rains the water is channeled to where it is of most use and least nuisance. This can be as simple as making sure paths have a camber or slope so water runs off them rather than along them
Water your plants in the early mornings and evenings when there is less sun, this helps prevent scorching the leaves and allows the plants to take up more water before it evaporates
If you must use a hose fit good quality sprinklers which will distribute the water evenly and close to the ground in large drops to reduce puddling and evaporation loss ( the bigger the droplet the smaller its surface area compared to its volume hence less evaporation)
Place water butts under greenhouse and garage gutters and if practical fit automatic irrigators connected to these for the greenhouse plants
Mulch plants where possible to retain moisture in the soil
Think about using drought tolerant or shade loving plants to reduce the amount of watering required
Try to select plants which are native to your area so they are used to the local conditions
Try to irrigate using ‘leaky’ pipes or drip feed systems, they will deliver water directly to the plant roots and not waste it in evaporation
Trees and large shrubs need a lot of water so bury a short piece of hose or a plastic bottle with its base cut off upside down next to the tree and water through these. This will get the water straight to the roots where it is needed
This list could be endless but these few measures could make a big difference.
For further information we recommend a couple of sites:
http://aggie-horticulture.tamu.edu/earthkind/drought/water/
or
http://www.greenlivingtips.com/articles/242/1/Saving-water-in-the-garden.html