Measurements: Water Potential


Small and Fast

With an active surface of only 0.5 cm2 and a diameter of 5 mm the ceramic tip has all advantages of small dimensions: little soil disturbance, punctual pick-up and fast response.


Extended Range

The special version T5x can achieve a measuring range of 200 kPa.

The T5 can be installed in any position and orientation. Bubbles are easily detectable through the transparent shaft. Output signals are balanced.


Typical Applications

  • Punctual measurement of water potential
  • Miniature lysimeter studies, together with micro samplers and soil temperature probes
  • Determination of pF/wc and K/Psi in soil columns, soil cores or soil sampling rings
  • Determination of leachate and capillary water movements
  • Controlling irrigation
  • Nursery experiments
  • Measurements in the upper soil horizons in the field
  • Monitoring with data loggers
  • Spot your readings in with the INFIELD7



  • Accurate zero-tension reading
  • Fast response: With sufficient filling, the T5 responds within 5 seconds to an applied air pressure change of 0 to 85 kPa
  • Most standard T5's reach a range of at least 150 kPa when delivered.



  • Not for dry soils
  • Not frost resistant
  • In-field applications require impact protection


See how to refill a T5 Tensiometer from UMS

Part number 45300


Various lengths available (standard 70 mm)

**Please indicate shaft/cup length on your order!**

POWER SUPPLY 10.6 VDC (5 - 15 VDC), stabilized
ELECTRONIC PRINCIPLE Asymm. Wheatstone full bridge

Piezoresistive pressure transducer

max. overpressure ± 3000 hPa

STABILITY 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 0 to 85 kPa (ca. pF 2.9)

minus shaft/cup length: 1 cm = 0.1 kPa

ACCURACY + 0.5 kPa

-100 kPa = -100 ± 3 mV

0 kPa = 0 ± 3 mV

85 kPa = 85 ± 3 mV

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.

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



  MPS-6 MPS-2 T5/T5x* T4 T8 TS1
COST $$ $ $$$ $$$ $$$$ $$$$$
ACCURACY ± 10% of reading + 2 kPa from -9 to -100 kPa ± 25% of reading + 2 kPa from -9 to -100 kPa ±0.5 kPa ±0.5 kPa ±0.5 kPa ±0.5 kPa
RANGE -9 to -100,000 kPa -9 to -100,000 kPa +100 kPa to -85 kPa (-200 kPa*) +100 kPa to -85 kPa +100 kPa to -85 kPa +100 kPa to -85 kPa
POWER REQUIREMENTS 3.6-15 V, 10 mA 3.6-15 V, 10 mA 5-15 VDC 5-15 VDC 3.6 V-15 VDC 5-15 VDC
MEASUREMENT OUTPUT Digital SDI-12 Digital SDI-12 Analog Analog Digital SDI-12, RS-485 Digital SDI-12, RS-485
METHOD USED FOR DETERMINING WATER POTENTIAL Capacitance of a ceramic matrix, 6 point calibration Capacitance of a ceramic matrix, 2 point calibration Piezoelectric pressure sensor, Wheatstone full bridge

- Long term research studies

- Natural environment monitoring

- Low cost irrigation monitoring

- Column & Spot Measurements in the Laboratory

- Small point measurements

- Long term field studies

- Vadose zone hydrology

- Long term field studies

- Vadose zone hydrology

- Long term field studies

- Vadose zone hydrology

- Monitoring in remote sites


Auger Kits for Pore Water Samplers and Tensiometer

The cutting edge of the auger has a tapered tip similar to the shape of a Tensiometer or pore water sampler.  Thus, the bore hole is large enough to insert the shaft, but the cup will have a tight and perfect fit to the soil.

The not recommendable slurrying of the cup with quartz clay can be avoided.

A divisible auger set includes:

  • Cutting edge with tapered tip
  • Handle with hammering head

Parts have threaded connection and can be extended with one or more 100 cm extension rods.


  • Simplifies installation of shafts
  • Avoids slurrying
  • Multipart - divisible - extendable
  TB-20 TB-25
  • Cutting Edge
22 mm dia. x 50 cm 26 mm dia. x 50 cm
  • Tip
20 mm dia. x 5.6 cm 24 mm dia. x 5.6 cm
  • Total length
1.25 m 1.5 m
  • For shafts with
20 mm dia. 24 mm dia.
Part no. TB-20/125 TB-25/150
Extension rod Part no. TBE-100  


Infield 7

The INFIELD7 is a multi-functional handheld read-out unit for all UMS tensiometers. Download readings to PC with accessory USB converter


  • Memory for 250 readings
  • Vertical water column compensation for Tensiometers
  • T8 and TS1 configuration
  • Carrying case
  • 4 AA batteries

Looking for a data logger for long-term installations? Contact Decagon support at 1-800-755-2751.


Lab Refill Kit for Tensiometers

Lab refill kit for tensiometers (includes T4 and T8), includes stand with clamps, adapter that fits sensor body, 500 mL bottle, pressure gauge, tubes, beaker, and refilling syringe.

Refill Kit for External Refillable Tensiometers

Refill kit for external refillable tensiometers (includes T4e and T8), includes hand-operated vacuum pump, 500 mL bottle, refill syringe, tubes and valves.

T5 Refill Kit & Tool Set

The T5 Refill kit & tool set includes refill equipment needed to properly refill your T5 tensiometer. It also includes an Auger kit and connecting cable for Campbell Scientific Dataloggers.

Request Support

Email: support@decagon.com
Phone: 509-332-2756
Fax: 509-332-5158