Groundwater

Groundwater is water underneath most land and is the most available source of freshwater on earth.

It comes from rain and goes to an underground water storage called aquifers, then eventually flow into rivers, lakes or the ocean.

Overall, 22% of the world's freshwater is groundwater.

In the Northern Territory (NT), 90% of the water supply comes from groundwater.

This water is extracted by drilling wells before being pumped out through a bore. There are around 35,000 water bores in the NT.

Groundwater quality changes in each place so not all water is suitable for drinking. You must check the quality of groundwater in your area.

Effects of climate and recharging

Water not used by plants goes through soil until it reaches the saturated zone.

This is called groundwater recharge, and it happens a lot during heavy rain.

When this happens, the water level in aquifers can go up and down.

Water can also get into aquifers through rivers and flooded areas.

Rainfall

Rainfall is very seasonal in the NT, with most rain falling in the wet season.

Central Australia has low rainfall and can happen at any time of the year.

The wet season rain is good for groundwater supply. But overuse of groundwater can harm springs, soaks, and rivers.

For information about springs and desert waterholes that are groundwater-fed, read groundwater-dependent ecosystems.

Data and monitoring

Proper management of groundwater depends on good quality monitoring data.

Groundwater levels are measured by the standing water level in monitoring bores.

Levels vary as groundwater moves from high to low zones due to gravity and recharge from rainfall.

To check levels that change slowly over time, the distance is measured from the top of a bore to the water level inside it.

Dynamic groundwater levels are measured on an hourly basis by instrumented bores.

You can get data from past and current sites using the water data portal.

To drill a bore, you must have a drilling licence.