Water potential in the lab


Let’s get straight to the point

If you need point-to-point water potential measurements in soil columns, soil cores, or sampling rings there aren’t a lot of options.  Traditionally, incremental measurements to trace water or contaminant flow down the length of a soil column were impossible to make.  Scientists tried everything from imposing water potentials at the top and bottom of the column to slicing it into disks that they could then measure. None of these methods were efficient, effective, or even accurate. There was simply no instrument small enough to make these measurements.  Until now.

It’s a small wonder

With the T5 Tensiometer, we put our 25 years of expertise to work in the smallest space possible: a ceramic tip with a surface area of only 0.5 cm2.  The T5’s minor footprint allows major advantages over larger tensiometers such as very little soil disturbance and an incredibly fast response time.  Not only that, because of its small size, it’s the only tensiometer in the world that can extend its measuring range. No more trying to handle selective measurements in the field or small samples with oversized tensiometers.  The T5 is small enough and precise enough to perform excellent point to point measurement of water potential in even the tightest spaces.

Not faster than a speeding bullet, but almost

The T5 Tensiometer has a superheroic response time of only 5 seconds for a pressure change of 0 to -85 kPa. It reacts much faster to changing soil conditions because of its small water volume, enabling you to measure even the most minute changes in water potential—something lower-quality tensiometers cannot do. It measures matric potential exactly within the range of most water movement, helping you understand whether water will move and where it will go.

The cavitation problem—solved

The T5 Tensiometer has a measuring range of at least 100 to -85 kPa. But the T5x version is the first pressure transducer tensiometer, which increases the measuring range of the matric potential to nearly -300 kPa. How is this possible? Normally, when a tensiometer reaches -85 kPa, the water boils, forming an air bubble. The air bubble expands and contracts with changes in pressure, making the tensiometer unable to measure suction. But the specialized T5x is able to retard the boiling point, extending the measurement range well beyond normal limits.

Easy does it

To save you time and effort, the T5 can be installed in any position and orientation, plus it comes with a miniature auger to ensure as little soil disturbance as possible.  For spot measurements, just auger a 5 mm hole and insert the tensiometer.  It’s that easy.  For long-term measurement, the T5 connects to any Campbell Scientific data logger.  On top of all that, bubbles are easily detectable through the transparent shaft, making it easy to see when it’s time to refill.

Small tensiometer, big benefits

For more than a quarter of a century, METER has been the leading expert in the development of tensiometers with over 10,000 sold.  Nobody in the world makes an instrument this small, this simple, or this precise.  Trust the T5 for fast, accurate point-to-point water potential in all your tightest spaces.

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  • Laboratory tensiometer
  • Small and fast
  • Little soil disturbance
  • Extended range with T5x model
  • Install in any position or orientation
  • Bubbles easily detectable through the transparent shaft
  • Output signals are balanced
  • Accurate zero-tension reading



Total length

4 cm + shaft length

Current consumption

~1.3 mA (at 10.6 V)

Shaft with cup

Various lengths available (standard 70 mm)
**Please indicate shaft/cup length on your order**

Power supply

10.6 VDC (5 - 15 VDC), stabilized


Shaft diameter: 5 mm
Body diameter: 20 mm

Electronic principle

Asymm. Wheatstone full bridge

Shaft material



Piezoresistive pressure transducer
Max. overpressure ± 300 kPa


Typical shift < 0.5% p.a.


Various lengths available (standard 5 m)
**Please indicate cable length on your order**

Temperature shift

Temperature-compensated, typical shift 0.5% FS over 25 K


100 to -85 kPa (ca. pF 2.9)
minus shaft/cup length: 1 cm = 0.1 kPa


0.1 kPa


± 0.5 kPa


~2.5 kOhm


100 kPa = -100 ± 3 mV
-85 kPa = 85 ± 3 mV
at 10.6V excitation

Accurate values according to the calibration certificate. Galvanic sensor insulated from soil water. Depending on the installation orientation of the T5, the hydrostatic potential of the shaft length has to be considered

Data logger compatibility

Campbell Scientific, Infield 7

Measurement principle

Soil water tension, transmitted via ceramic cup into the tensiometer, onto the water and pressure transducer, producing a continuous analog signal

California requires the following notice:

⚠️ WARNING: This product may contain chemicals including ethylene glycol, lead, nickel, styrene and cadmium, which are known to the State of California to cause cancer, birth defects or other reproductive harm. For more information, go to www.P65Warnings.ca.gov


Have a question? Our team is ready to help!

We manufacture, test, calibrate, and repair every instrument in-house. Our scientists and technicians use the instruments every day in our product testing lab. No matter what your question is, we have someone who can help you answer it.

Email Europe: sales.europe@metergroup.com
Phone US: +1 509-332-5600
Phone Europe: +49 89 12 66 52 0

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