Garden Bores
Garden bores draw water from shallow groundwater, generally to about 50 metres in depth, although some can be as deep as 100 metres. This source of water is fed by rainfall, which percolates into the ground across most of the Swan Coastal Plain. Garden bores can provide a fit for purpose water source and can take pressure off scheme drinking water supplies.
It is estimated that there are about 164,000 garden bores in Western Australia, with about 90% in the Perth metropolitan area. These bores supply over 20% of all household water.
Some areas in Perth are unsuitable for a garden bore. These areas are generally:
• close to wetlands;
• near the foothills and places with clay or alluvial soils;
• within about 200 metres of the Swan River estuary or the ocean, including the Cottesloe Peninsula where salt water can be drawn into the bore;
• near industrial and waste disposal sites where groundwater may be contaminated; and
• in locations prone to acid sulphate soils.
Since February 2003 the State Government has supported the installation of garden bores through a Waterwise rebate to people in areas where bores are suitable according to the Perth Groundwater Atlas. Over 21,000 rebates have been granted since the program began (about 5,000 a year).
Garden bores depend on rainfall to recharge groundwater. As rainfall in the South West of Western Australia has fallen over the past 30 years, we need to use this resource wisely. The Department of Water is currently updating the Perth Groundwater Atlas. Rebates for garden bores will no longer be available for areas deemed unsuitable for additional bores.
In October 2007, the State Government implemented permanent Water Efficiency Measures (WEMs) that impact the use of garden bores. In the Perth region, garden bores are now subject to a three-day a week sprinkler roster system. This is adequate to maintain a garden without wasting water and avoids the risks of overuse.
The potential for additional garden bores is generally decreasing due to a number of factors, including:
- introduction of the three day a week sprinkler rostering system for bores;
- loss of rebate in some areas;
- smaller lot sizes making them less economical; and
- waterwise gardens requiring less water to maintain.
It is estimated that between 2,000 to 3,000 new garden bores will be added each year over the next 10 years.