Groundwater bore records: where to find and read them

Registered bore records are held by each state: the Groundwater Database in Queensland, WaterNSW in New South Wales, Visualising Victoria's Groundwater in Victoria and WaterConnect in South Australia. They are the closest thing to direct evidence of what is under a site before anyone drills it. Each record is what a driller met at one spot: the materials, the depths where they changed, and often the standing water level. Read the logs within a few hundred metres of a property together and you get an indication of the likely profile, the depth to rock and the depth to groundwater.

The traps in interpreting them, such as perched water and single-day readings, have their own piece: seven common mistakes reading groundwater bore logs.

Where do you find bore records in QLD, NSW, VIC and SA?

Each state keeps its own database, and the Bureau of Meteorology combines them nationally.

State	Where the records are	What you can see
Queensland	Groundwater Database (GWDB), viewable on the Queensland Globe registered bores layer	Bore reports with location, construction, strata log, water levels and water quality
New South Wales	WaterNSW groundwater records, built from the bore construction reports drillers lodge	Work summaries, driller's logs and water levels for registered works
Victoria	Visualising Victoria's Groundwater and the state Water Measurement Information System	Bore locations, logs and water level records
South Australia	WaterConnect groundwater data	Drillhole details, logs and water levels
All states	Bureau of Meteorology National Groundwater Information System (NGIS), through the Australian Groundwater Explorer	Bore locations, lithology logs and construction logs combined across states

None of these holds every bore ever drilled. Older bores, unregistered bores and most geotechnical boreholes from building sites are often missing, so a blank patch on the map does not mean nobody has drilled there.

What is in a bore record?

A bore is a hole drilled to reach or monitor groundwater. Water supply bores, monitoring bores and investigation holes generally have to be registered, and the registration produces a record. It can include:

• The location, total depth and drilling date
• The standing water level: how far below the surface the water sat when it was measured
• A driller's log (also called a strata or lithology log) describing the soil and rock layers on the way down
• Construction details, such as the depth of the screen (the slotted section that lets water in)
• Sometimes water quality or yield

How do you read a driller's log?

Take each record in this order.

1. Location and distance. How far is the bore from the site, and is it on the same landform? A bore on the river flat says little about a lot on the ridge above it.
2. Date and purpose. A water supply bore drilled decades ago was logged to find water, not to describe soil for footings.
3. The log itself. Drillers describe what came up in their own terms: "clay", "sandy clay", "shale", "weathered rock". These are not the descriptions a geotechnical engineer uses under AS 1726 (the Australian standard for describing soil and rock on site investigations), so read them as a general indication of the profile, not a classification.
4. Depth to rock. Where the log changes from soil to weathered rock is often the most useful number for footing and excavation planning.
5. Water level and screen depth. Check when the level was measured and where the bore was screened. A level in a deep screened bore may describe a different water body from the shallow groundwater that matters for a house.

Then compare several nearby bores. Consistent depths to rock and water across several logs carry more weight than any single record.

Why does groundwater matter for footings and slabs?

Strength. Saturated clay is softer and weaker than the same clay dry, so a water table near footing depth can mean weaker founding soil than expected.

Excavation. Dig below the water table and the hole fills. That means dewatering (pumping water out while the work is done), shoring and delays, all of which belong in the scope.

Soil movement. On reactive clay soils, seasonal wetting and drying makes the ground swell and shrink under a slab. A shallow or fluctuating water table changes those moisture conditions, which matters for the AS 2870 site classification and footing design.

Acid sulfate soils. On coastal lowland, lowering the water table or digging into it can expose acid sulfate soils to air and generate acid. A shallow water level on a low coastal site is often the first sign they need checking.

What can bore records tell you, and what can't they?

They are good for:

• An indication of depth to water. If nearby bores consistently show water at a few metres, the site may be similar, subject to landform and season.
• A picture of the geology. Logs show whether the area is likely to be sand, clay, rock or a variable mix.
• Scoping a site investigation. An engineer plans borehole depths and groundwater observations better knowing what nearby bores found, including whether the job needs groundwater monitoring at all.

They cannot:

• Describe the exact site. The nearest bore might be a street away, on a different landform, drilled decades ago.
• Show seasonal change. A level measured in a dry spell can be very different from the same spot after a wet summer.
• Replace boreholes on the block. The site investigation decides the classification and the design groundwater assumptions.

For buying, feasibility or comparing sites, a desktop review shows whether water is likely to be an issue and whether excavation might need dewatering. For design, the site investigation takes over. What a geotechnical desktop study is covers where one ends and the other begins.

Common questions

How do I find groundwater bore records for a property in QLD or NSW? In Queensland, open the registered bores layer on Queensland Globe, which draws on the state Groundwater Database. In NSW, registered bore records are held by WaterNSW, and the Bureau of Meteorology's Australian Groundwater Explorer shows bores from every state on one map. Search around the address for nearby bores and download their logs. A desktop report pulls the nearest records for one address into a single document.

Does a high water table affect my AS 2870 site classification? It can. The classification is mostly about how much the soil moves with moisture change, and groundwater affects both the moisture conditions and the strength of the soil. Where a shallow water table comes with soft soils, the site may be Class P (a problem site needing specific engineering design). The site investigation decides.

Can bore records replace a site investigation? No. They give an early indication of depth to water and the local geology, but they describe other holes, not the site. A geotechnical engineer still needs to investigate the site itself for the classification and footing design.

Before you drill, dewater or design a footing, it helps to know what nearby records show. Generate a desktop report for the address or see a sample report.

LayeredGeo compiles geology, soils, groundwater and site data into an automated geotechnical desktop report for any address in Queensland, New South Wales, Victoria and South Australia.

About this article. Published by LayeredGeo. It is general information about how property and ground conditions are assessed in Australia, not engineering, planning, legal or financial advice, and it is not specific to any property. Check anything that matters against the source dataset or a suitably qualified professional before you rely on it. If you spot something wrong, tell us at hello@layeredgeo.com.au and we will fix it.

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