Piezometers can prove priceless in tracking pore water pressure in geotechnical and environmental applications. Two of the most common and versatile types are the hydraulic piezometer and the vibrating wire piezometer. Each has it’s own advantages and ideal uses and understanding those differences is the key to designing an effective and accurate monitoring system.

In this guide, we break down how each model works, where they perform best and how Monitel can support ongoing monitoring on your site. For more information, please contact our team.

What Is a Piezometer?

A piezometer is a geotechnical sensor used to measure pore water pressure. Accurate and reliable piezometer data is essential in evaluating slope stability, settlement, seepage and groundwater changes in critical applications like tailings dams, mine pit walls and borehole monitoring.

Piezometer data serves many purposes. You might be looking to prove compliance with WA regulations or are perhaps looking to improve engineering design. Regardless, proper sensor selection can have long term implications for site safety and data quality.

How They Work

They might be in the same “family” of sensors, but the HP and VWP function in two different ways.

Hydraulic Piezometers

A hydraulic piezometer operates with a water-filled system and a porous ceramic tip that allows pore pressure to equalise. Pressure is transferred through hydraulic tubing and into a surface gauge such as a Bourdon gauge or pressure transducer. They are non-electrical at depth, providing stability in chemically aggressive and electrically noisy environments.

Vibrating Wire Piezometers (VWP)

In a VWP, a diaphragm is connected to a tensioned wire. As pore pressure changes, the wire’s vibration frequency shifts – those shifts are then recorded and converted into readable pressure data. These sensors are ideal for automated or remote monitoring and are resistant to electrical interference, making them a popular choice for deep borehole installations and long-term systems.

Key Differences and Comparisons

Feature	Hydraulic Piezometer	Vibrating Wire Piezometer
Power at Depth	No electricity required	Requires electrical readout
Signal Output	Surface-based gauge or 4-20mA	Frequency-based data logger
Best For	Low-permeability soils, corrosive or high EMI zones	Remote monitoring, deep boreholes, long-term use
Sensitivity	Excellent in soft clays or slow-draining soils	Excellent overall, especially for changing pressure conditions
Installation	More labour-intensive (requires filling system)	Easier in complex sensor arrays
Durability	High resistance to corrosion and EMI	Rugged, stable, but less suited to chemical attack

Hydraulic or VWP? It Depends on Your Project

When to Choose a Hydraulic Piezometer

Tailings Dams: In fine-grained, low-permeability zones, hydraulic piezometers provide stable readings where electronic sensors may struggle
Corrosive Environments: Ceramic tips and non-metallic tubing hold up well in chemically aggressive tailings or groundwater
High EMI Zones: If your site houses heavy electrical infrastructure (like pumps or conveyors), hydraulic sensors will avoid any signal interference they produce

When to Choose a Vibrating Wire Piezometer

Deep Borehole Monitoring: VWPs are compact, accurate and can be easily integrated with multi-point borehole systems
Automated Monitoring: These sensors pair easily with data loggers, solar panels and remote telemetry for real-time insights
High-Temperature Zones: Monitel stocks high-temperature models designed for buried infrastructure, geothermal environments or tailings with heat build-up

Monitel’s Sensor Range

Hydraulic Piezometer

We stock an HP model designed by Soil Instruments. A flushable, passive sensor, it boasts a ceramic filter tip and twin fluid-filled hydraulic tubing. With an operating range of –50 kPa to 2000 kPa, it can support positive and negative pressure readings and maintains long-term stability in harsh subsurface environments.

You can read more here.

Vibrating Wire Piezometers

Monitel can supply a range of vibrating wire piezometers, each designed to address a unique environmental condition found in Western Australia:

VWP‑3000 Series: Designed for geotechnical and structural monitoring, with multiple filter options, 0.025 % resolution and long cable signal integrity
W9 Vibrating Wire Piezometer: A compact, robust sensor built for high-accuracy readings from –50 to 4000 kPa, with built-in temperature compensation and surge protection
W16 Kompakt Piezometer: A small‑diameter unit (19 mm) ideal for constrained installations, available in pressure ranges up to 1000 kPa with hermetic sealing and thermistor temperature sensi

Monitel’s Approach

At Monitel, we pride ourselves on a technology-agnostic approach to sensor selection. We match our systems to site conditions, reporting requirements and budgets – not brand allegiance. Whether your site suits a hydraulic or vibrating wire model, you can be confident your monitoring system is set up for success.

Our team can also support you with:

Sensor installation
Piezometer potting
Connection to remote data loggers and cloud-based dashboards
Compliance-ready reporting for mining, civil and environmental projects

Get in Touch Today and Learn More About Groundwater Piezometer Monitoring

If you’re unsure whether your project needs a hydraulic or vibrating wire piezometer, it’s important to seek professional advice. Monitel will review your soil conditions, project scope and monitoring goals to develop an effective and compliant monitoring system.

To speak with our team, please get in touch.

Vibrating Wire vs Hydraulic Piezometer: Which is Right for Your Project?