Groundwater

Groundwater is found below the earth’s surface and includes water from bores, springs, wells and other sources.

There are risks in using groundwater#

Groundwater may contain disease-causing microorganisms that can make people ill. Some supplies contain high levels of chemical contaminants, such as arsenic, which can cause illness in people who drink the water. Groundwater with high levels of salts, such as sulfate and nitrate, can also be harmful.

Other dissolved salts can make water hard, leading to scale build-up and corrosion in pipes. This can release harmful metals such as lead and copper into the water.

Check before you use it#

If a mains water supply is available, use it instead of groundwater.

If you rely on groundwater, find out about local groundwater quality and whether it is suitable for your intended use. It is important to understand:

• What treatment is needed to make the water suitable for its intended use. Different uses need different treatments. For example, a treatment that removes harmful microorganisms does not remove other contaminants that may be present.
• How to maintain and monitor your supply so that it stays safe to use.

Anyone with a private water supply should have a water supply management plan to make sure the water is suitable for its intended use and does not pose a health risk.

What affects groundwater quality#

Groundwater quality can be influenced by the time of year, the depth at which the water is stored, the catchment area (the land from which water is collected and channelled into the groundwater store) and how that land is used.

Hazards that can contaminate groundwater include:

• Sewage and animal waste
• Agriculture, including pesticides and fertilisers
• Industrial pollution
• Floodwater and seepage from rubbish tips
• Polluted stormwater and chemical spills
• Contaminated surface waters
• High levels of naturally occurring chemicals and radioactive substances

Health risks#

The health risk from groundwater depends on the type and concentration of contaminants, and on how often, for how long and in what ways people are exposed (for example, drinking, inhalation or skin contact).

Disease-causing microorganisms in water supplies can cause diarrhoea, vomiting or other gastrointestinal illness. Some can lead to more serious illness, and even death. The people most at risk from unsafe water are the elderly, young children, pregnant women and people with weakened immune systems.

Reducing the risk#

To reduce the risk of ill health from contaminated groundwater:

• Where a mains supply is available, always use it for drinking.
• When mains water is not available, choose the next best source of water. You may need to treat it to make it safe to drink.
• If you live where contamination is likely, such as an area of previous industrial use, do not use groundwater for domestic purposes such as drinking, brushing teeth, preparing food, bathing, watering fruit and vegetables, or filling spas and swimming pools.
• Avoid water from shallow bores, because of the higher risk of contamination.
• If you are thinking about using groundwater to prepare infant formula, talk to a child health nurse or doctor first, as nitrates in groundwater can pose a risk to bottle-fed babies.
• If you have a private water supply, keep an up-to-date water supply management plan and assess your supply for contamination regularly.

Maintaining bores#

If you use bore water, make sure that:

• The well-head is above ground.
• The bore is protected from contamination by surface run-off, channel water, irrigation water, leakage from sewer pipes or septic tanks, stormwater and graywater drainage, shallow underground seepage, and flooding.
• The borehole is properly cased (lined, for example with a PVC pipe).

If possible, store drinking water in an above-ground tank rather than an underground one. To avoid cross-contamination, keep any mains drinking water plumbing separate from all other plumbing or pipe systems, and make sure all pipe joints are properly sealed.

Key points#

• There are risks in using groundwater.
• Groundwater may contain disease-causing microorganisms that can cause illness.
• If mains water is available, use it instead of groundwater.
• Disease-causing microorganisms in water supplies can cause diarrhoea, vomiting or other gastrointestinal illness.
• When mains water is not available, choose the next best source of water.