Bore & Groundwater Quality: Test First, Treat Second

Bore water can look perfectly clear and still contain dissolved chemicals, salts or microorganisms that you cannot see.

For Australian households, groundwater can be a valuable water source. But being underground does not automatically make it purified or safe to drink.

Its quality depends on local geology, surrounding land use, bore construction and what happens during storage and distribution.

Before choosing a filter, the most useful first step is simple:

Find out what is actually in the water.

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Where does bore water come from?

Groundwater forms when water moves beneath the surface and collects in the spaces and fractures within soil, sediment and rock.

An underground formation that can supply usable quantities of groundwater is called an aquifer. Bores and pumps bring that water to the surface.

As water travels underground, it can dissolve minerals and other naturally occurring substances. It may also encounter contamination from human activities.

This is why a neighbour’s satisfactory water report cannot establish that your bore is suitable for drinking.

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Doesn’t the ground naturally filter the water?

Soil and rock can remove some particles as water moves through them. However, this process does not reliably remove every harmful microorganism or dissolved chemical.

Groundwater can be affected by sewage, animal waste, agricultural runoff, industrial pollution and naturally occurring substances such as arsenic.

Contamination can also move underground and persist long after the original release. Clear water and a clean-looking property do not rule out contamination beneath the surface.

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Is clear bore water safe to drink?

Appearance, taste and smell cannot establish safety.

NSW Health recommends that groundwater should not be used for drinking, cooking or personal hygiene—including teeth cleaning and bathing—without testing and appropriate treatment, including disinfection.

Where a public drinking-water supply is available in urban areas, NSW Health recommends using it for these purposes.

An untreated garden bore should therefore not automatically become a household drinking supply.

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Are deeper bores safer than shallow bores?

Shallow or unconfined groundwater is generally more exposed to contamination from surface activities.

A properly constructed bore drawing from a deep, confined aquifer may have a lower microbial risk. However, deeper water can still contain substantial dissolved minerals, metals or naturally occurring radioactive substances.

Bore depth alone does not establish drinking-water quality. The source needs a chemical assessment as well as consideration of microorganisms.

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What are the possible health implications?

The risks depend on the substance, its concentration and the amount and duration of exposure. Not every bore contains all—or any—of the following problems.

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Microorganisms and gastrointestinal illness

Contamination from sewage, animal waste or surface water can introduce disease-causing organisms.

These can cause gastrointestinal illness, including diarrhoea, vomiting and abdominal discomfort. Water that is suitable for irrigation may still be unsuitable for drinking or food preparation.

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Nitrate and young infants

Nitrate can enter groundwater from fertilisers, animal waste and wastewater.

Elevated nitrate is particularly concerning for young infants because it can interfere with the blood’s ability to carry oxygen—a condition called methaemoglobinaemia.

Do not use untested bore water to prepare infant formula. Boiling does not remove nitrate and can increase its concentration as water evaporates.

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Arsenic and long-term exposure

Arsenic can occur naturally in groundwater because of local geology.

Long-term exposure to elevated inorganic arsenic in drinking water can cause skin changes and increase the risk of cancers, including skin, bladder and lung cancer.

This is a reason to test where arsenic is relevant—not a reason to assume every Australian bore contains dangerous levels.

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Salinity and sodium

Salty groundwater can be unpleasant to drink and unsuitable for some household uses.

Sodium in drinking water may also matter for people following a medically prescribed low-sodium diet. A laboratory result is more useful than taste alone when assessing that contribution.

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Hardness is a different issue

Calcium and magnesium can cause scale without making the water toxic. Hardness is primarily a maintenance concern and should not be confused with contamination by arsenic, nitrate or pathogens.

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What should bore water be tested for?

Ask a NATA-accredited laboratory to help select a drinking-water test panel appropriate to the property.

Explain where the bore is located, how the water will be used and whether nearby activities could affect it.