How To Monitor Well Water: Techniques, Tools, And Best Practices

Monitoring groundwater well water is essential for understanding aquifer behaviour, protecting receptors, meeting regulatory obligations, and guiding remediation or development decisions. Whether you manage anenvironmental program or deliver geotechnical investigations, a robust monitoring approach gives you defensible data that stands up to regulator scrutiny and design needs. This guide explains what a monitoring well is,how to monitor well water effectively, the difference between a borehole and a monitoring well, and the practical steps to achieve reliable results in Australia.

What is a monitoring well?

A monitoring well is a purpose-built installation designed to measure groundwater levels and collect representative groundwater samples from a defined interval. Unlike production bores that are built to yield water,monitoring wells are engineered for accuracy, repeatability, and minimal disturbance. They typically consist of a screened interval positioned across the target aquifer zone, riser casing to surface, filter pack and bentoniteseals to isolate the screen from other strata, and a secure surface completion to protect the wellhead. Correct construction is critical; poor seals or wrong screen placement can short circuit aquifers or bias samplechemistry.

Borehole vs monitoring well, what is the difference?

A borehole is simply a hole drilled into the ground. It may be temporary, used for coring or testing, or later converted to a well or instrument. A monitoring well is the finished, engineered structure installed within a boreholefor long term groundwater level and quality monitoring. The conversion process includes installing the screened casing, filter pack, seals, grout, and surface protection, then developing the well to restore natural flow to thescreen. Put simply, a borehole is the pathway, the monitoring well is the instrument.

How do you monitor well water?

Groundwater monitoring involves two core activities, measuring water levels and obtaining water quality samples. For both, you need to respect purging and stabilisation, minimise disturbance, and document everything.

Water level measurement

Use an electronic water level meter or pressure transducer. Manual dip measurements provide immediate data; datalogging transducers capture continuous hydrographs to assess recharge, barometriceffects, or tidal influences.

Record time, datum, tape correction, and temperature. Correct for density where high salinity or temperature gradients exist.

PurgingRemove stagnant water from the well to draw formation water across the screen. Low flow purging using a peristaltic pump, bladder pump, or low drawdown submersible is preferred to minimiseturbidity.

Stabilise field parameters before sampling, track pH, EC, temperature, DO, ORP, and turbidity, and confirm three consecutive stable readings.

QA/QCInclude equipment blanks, trip blanks for VOCs, field duplicates, and rinsate blanks as appropriate. Calibrate probes daily and document methods, lot numbers for calibration standards, and maintenance.

Development and rehabilitationNewly installed wells require development to remove fines and ensure hydraulic connection. For older wells, periodic rehabilitation may be needed if biofouling or precipitates increase turbidity or obscuretrue chemistry.

Types of monitoring wells

Your monitoring objectives dictate the well design.

Single screen wells

Most common for site compliance and plume tracking. Screen length is tailored to the thickness of the target interval; short screens improve vertical resolution.

Nested wells

Multiple wells in one cluster at different depths. Useful where vertical gradients or stratification are significant. Avoid shared annuli to prevent cross connection.

Multilevel systems

Discrete ports at multiple depths in one bore. Provide high resolution vertical profiling of hydraulic head and chemistry in complex stratigraphy.

Drive-point piezometers

Temporary or semi-permanent points installed rapidly for hydraulic head or screening-level chemistry in shallow formations.

Instrumented piezometers

Installations fitted with a vibrating wire piezometer or pressure transducer where continuous pore pressure data supports geotechnical assessments or dewatering design.

Drilling and installation

Hollow stem augers suit unconsolidated soils and allow clean installation with minimal fluid use. In difficult ground or where core quality matters, sonic drilling provides near complete recovery with lowdisturbance and reduced spoil, improving well placement and seal integrity.

Filter sands, bentonite chips or pellets, cement grout, and cement bentonite seals are specified to state guidelines and site risk.

Purging and sampling

Low flow pumps, flow cells with inline multi-parameter sondes, decontaminated tubing, and passive samplers where appropriate.

Water level meters, data loggers, transducers, and barologgers for density corrected head data.

Development and rehabilitation

Surge blocks and low flow pumping, plus dedicated redevelopment for fouled wells where iron bacteria, carbonate scaling, or fine migration is evident.

Best practice installation and sampling

Site conceptual model

Set screen depth and length using logs, CPT data, and hydraulic testing results. Target the correct hydrostratigraphic unit, avoid smearing of fines, and design seals to isolate discontinuities.

Construction QA

Record depths, materials, volumes, grain sizes, and tremie placement. Tag seals and grout returns. Photograph each step and log driller observations.

Development criteria

Target turbidity below project thresholds, typically <5 to 10 NTU for sensitive analyses, or stabilised turbidity trending downward where geology is naturally silty.

Low flow control

Maintain drawdown less than 0.1 to 0.3 m during purging where feasible. Use inline meters to confirm stabilisation before collecting samples.

Decontamination

Wash, rinse, and verify cleanliness between wells. Use certified clean tubing and clean gloves. Segregate equipment for different contaminant classes if needed.

Documentation

Maintain field forms, calibration logs, and sample registers. Capture weather, nearby activities, and anomalies to support data interpretation.

Regulatory context and reporting in Australia

Across Australian states and territories, regulators expect transparent methods, traceable QA/QC, and clear justification of well construction and sampling. Guidance is typically aligned to the National EnvironmentProtection (Assessment of Site Contamination) Measure and state EPA documents, with additional requirements for resource projects and infrastructure.

A practical monitoring report should include:

Objectives tied to the conceptual site model.

Well construction logs, survey to AHD, and screen/soil profiles.

Water level data with barometric corrections where applicable, and hydrographs for longer monitoring programs.

Field parameter stabilisation records, purging rates, and sampling methods.

Laboratory certificates, QA/QC results, and data validation flags.

Data interpretation, plume mapping, trend analysis, and compliance against screening criteria.

Recommendations for further investigation, remediation, or management.

When to use specialist techniques

Hydraulic testing

Slug tests and pumping tests provide transmissivity and storativity estimates, improving understanding of plume migration and drawdown impacts. Packer testing in fractured rock isolates intervals tocharacterise discrete features.

High resolution site characterisation

Direct push tools and continuous coring improve vertical resolution of contaminants and hydraulic properties, reducing uncertainty and optimising well design.

How Legion Drilling supports your program

Legion Drilling installs compliant groundwater monitoring wells across Australia and provides end to end support, from design input and drilling method selection to development, surveying, and handover documentationready for your sampling team. Our team brings deep experience in complex stratigraphy, constrained urban sites, and remote logistics. We routinely deliver defensible datasets for environmental compliance andgeotechnical design, integrating high quality drilling, careful sealing, and precise records so you can rely on every data point.

If you need help planning or installing monitoring wells, explore our monitoring well installation page for a detailed overview of methods, materials, and QA.

Accurate groundwater monitoring starts with the right well design, careful installation, and disciplined sampling. Define your monitoring objectives, place screens correctly, build robust seals, develop the well thoroughly,and verify stability before sampling. Document each step and present clear, defensible reports aligned to Australian guidance. When you partner with a specialist team, you reduce uncertainty and gain reliable data fordecisions. Legion Drilling can support you with compliant installations, suitable drilling methods for your geology, and practical field know how that keeps your project on schedule and your data regulator ready.

Internal links:

monitoring well installation: https://www.legiondrilling.com.au/groundwater-monitoring-well-installation

sonic drilling: https://www.legiondrilling.com.au/sonic-drilling-company

hollow stem auger drilling: https://www.legiondrilling.com.au/solid-and-hollow-stem-augers