Bore water

Just like rivers found on the earth’s surface, water in aquifers will flow in a particular direction. As it moves through the ground, it will dissolve minerals and may also pick up any contamination, such as nutrients, pathogens and pesticides.

Water sourced from deeper, confined aquifers is generally of higher quality than water from shallow, unconfined aquifers, which are susceptible to contamination originating from animals, pesticides and fertilisers and industrial processes.

Many households in Western Australia use a garden bore to take groundwater from the shallow, unconfined aquifer and use it to water small gardens. Garden bores help to reduce the demand for highly treated scheme water and, when used responsibly and not overused, they can help distribute the take of groundwater to reduce impacts on water levels. The water doesn’t usually require treatment because the water quality is fit for use on gardens and lawn.

A simple test to check if water from your garden bore is suitable for watering is a field pH test, which can be done with a swimming pool test kit of pH test strips. Bore water with a pH of less than 5 should be professionally tested to ensure it is safe to use.

Before installing a bore in the Perth metropolitan area, first consult the Perth Groundwater Atlas (external site) to identify groundwater conditions in your area. The Atlas can also be used to estimate the depth to water. If outside the metropolitan area, contact the regional office of the Department of Water and Environmental Regulation (external site) for local water conditions.

You should also check the Contaminated Sites Database (external site) to ensure you are not drawing water from a known contaminated site.

Bore water can be suitable for domestic non-potables uses, such as toilet flushing, car and clothes washing, as well as irrigating vegetable gardens.

If bore water is your only water supply, or you rely on it to drink when your rainwater supply runs out, you should test the water at least once a year for chemical and microbiological contamination by a National Association of Testing Authorities (NATA) registered laboratory (external site).

Bore water should never be used for drinking, bathing, watering edible plants, filling swimming and paddling pools, food preparation or cooking unless it has been tested and treated to the extent necessary for the intended use.

Can I fill my swimming pool with bore water?

It is preferable to fill your pool or spa with scheme drinking water because it is treated and safe, good quality water.

If you use bore water, however, you will need to increase the quantity of chemicals you use (especially if the water contains a lot of iron) and this will add to your costs. Bore water may also cause staining, due to the dissolved salts and metals.

It is not usually necessary to treat bore water providing it:

• has a pH greater than 5
• is colourless and odourless and
• will only be used to water the garden, wash cars and flush toilets.

Chlorination is the most reliable way to ensure drinking water is free from microbiological contamination. Refer to water tanks on your property for advice on chlorine dosing water storage tanks.

Contact a NATA-accredited laboratory and ask for a Standard Drinking Water Test (PDF 142KB) for your bore water supply.

Bore water used for domestic non-potable uses, should be measured against the ‘Levels for garden irrigation’ as provided in the Department of Environment Regulation Contaminated Sites fact sheet 6: Contaminated groundwater – could my garden bore be affected? (external PDF 540KB).

Water intended for drinking, food preparation or showering should be measured against the Australian Drinking Water Guidelines (external site).

The Department of Health is also able to interpret laboratory results and provide you with advice on how to make water safe to drink.

Microbiological and chemical laboratories may also be able to assist you with additional technical advice. However, they are not in a position to provide you with health related advice.

Is bore water protected from contamination?

Bore water can be naturally contaminated by minerals, chemicals, bacteria and viruses. However, human activity usually has the greatest impact on shallow ground water quality as a result of:

• excessive or inappropriate use of fertilizers, animal manures, pesticides and insecticides
• poorly maintained septic tanks and other liquid waste disposal systems
• leaking fuel and chemical tanks
• intensive agriculture, industry or mining
• leaching from waste disposal areas
• accidental spills of chemicals.

Bores operated by licensed water providers such as the Water Corporation (external site) for drinking water are protected from contamination as they are located:

• within aquifers (mostly confined and at depth)
• in areas with restricted development and land usage
• are controlled by catchment management plans.

Can I tell if my bore water is contaminated?

It is not always possible to tell if your bore water is contaminated. Signs of contamination may include:

• unusual taste
• a low pH (acidic water)
• a chemical, sewage, petrol or ‘rotten egg’ smell
• soap suds/foaming around sprinkler outlets
• abnormal colour or sediment
• dying or wilting plants
• animals show a reluctance to drink.

If this occurs contact your local Environmental Health Officer.

Are all bore water contaminants a health risk?

Some contaminants are simply a nuisance as they cause staining, or may have an unpleasant smell or taste. An example of this can be found in some metropolitan areas where iron oxide leaches out of the soil causing a red brown stain on walls and footpaths.

Other contaminants such as nitrate, arsenic, pesticides and petroleum products are of health concern, particularly if bore water is used for drinking, bathing, food preparation or watering of edible plants.

How can I reduce the risk of contamination?

• Ensure your bore is installed with a protective cover and is surrounded by a concrete slab, with the wellhead protruding well above the ground. The slab should slope away from the bore, so that surface water does not drain into the casing.
• Regularly inspect your bore to check for signs of contamination.
• For rural or remote locations, ensure your bore is protected from livestock by perimeter fencing at a distance of 50 metres away.
• Locate the bore at least 30 metres from any wastewater system, such as septic tanks or aerobic treatment units.
• Ensure your bore is constructed by a licensed driller in accordance with the Minimum Construction Requirements for Water Bores in Australia 4th Edition 2020 (external site).
• This may also be a requirement of the license issued by the Department of Water for the bore.
• Do not use pesticides near your bore.
• Prevent wastewater from soaking into the soil near supply bores and clean up any chemical spills immediately.

• Use a licensed driller who is experienced with the soil and groundwater conditions of your area.
• Inspect your bore (including headworks, casing and pump) for signs of scaling, corrosion or damage.
• Maintain your pump in accordance with the manufacturer’s specifications.
• Measure the depth to the water level in the bore regularly, monthly is preferable. Take the measurement before turning the pump on and again immediately after turning the pump off. The depth of the pump may need to be lowered to keep the pump working properly. If either measurement is observed to be continually dropping over a period of more than one year, this may indicate that the pumping rate is exceeding the recharge rate of the aquifer. Over-pumping can lead to silting and the bore may stop working properly.
• Take a water sample regularly. Allow the bore to be pumped for at least 15 minutes before taking readings of pH and salinity (these can be done with an inexpensive field test meter) at the same time as checking the depth to water. Increased salinity may indicate that over-pumping is introducing salty water from another layer, or there is a hole in the bore casing. This could also mean that contamination is entering the bore that hasn’t previously been considered.

Many bores and pumps fail because they are poorly constructed, not maintained properly, or because gradual changes go unnoticed.

Installing and pumping water from a well increases the level of oxygen and nutrients in the well.

Bacteria thrive in these conditions and may form a biofilm, which captures chemicals, minerals, sands, clays and silts.

Iron can combine with oxygen and get trapped in the biofilm and sometimes the biofilm accumulates to the point that it reduces the bore yield.

Bores can be decontaminated and/or unclogged by using a range of chemical and physical processes.

For information on the materials and substances that can be used safely to treat your bore please refer to the Materials and Substances in Contact with Drinking Water factsheet (external link).

If the bore fails due to a structural problem, such as blockage, corrosion or collapse of casing materials (including screens), contact a licensed driller who can provide further advice on repair or redevelopment works.

Bore water cannot be connected to the scheme supply unless:

• a back flow prevention device separates the bore water from the scheme drinking water supply
• any connection to the scheme supply must be done by a licensed plumber
• all work must be done in accordance with Australian Standard AS 3500 Part 1.2 National Plumbing and Drainage (external site)
• pipes and materials used must be either food grade or Australian Standard AS 4020 ‘Testing of products for use in contact with drinking water’ (external site) approved.

Small-scale garden watering exemption

In Western Australia, bores are exempt from licensing if they’re used for irrigating small areas of garden and lawn and the water is taken from the shallow, watertable aquifer (such as Perth’s superficial aquifer).

Garden bores generally don’t require licensing because they are small bores, using a small amount of water compared to other licensed groundwater users, and they help spread the take of groundwater. They are however regulated through sprinkler restrictions and compliance actions.

For more information about garden bore licensing exemptions visit the Department of Water and Environmental Regulation website (external site).

When a licence to construct a bore and or to take groundwater is required

You do need a water licence from the Department of Water and Environmental Regulation if you are located within a proclaimed groundwater area and you:

• use a bore to irrigate areas of garden and lawn of 0.2 hectares or more (2,000 square meters or more)
• use a bore for commercial purposes, such as to grow produce or manufacture goods
• take water from an artesian aquifer (such as Perth’s mostly confined Leederville and Yarragadee aquifers).

For more information on how to apply for a groundwater licence visit the Department of Water and Environmental Regulation website (external site).

If a bore is damaged and can’t be fixed or is no longer needed, it must be properly decommissioned.

Filling the bore with grout or bentonite from the top to the bottom is the preferred method of decommissioning. This will eliminate any physical hazard (e.g. open holes) and prevent groundwater contamination.