WET-2 Sensor

    How to Buy
WET Sensor - measures moisture, EC and temperature Zoom
WET Kit – with carry case and HH2 readout unitWET Kit – including WET SensorWET SensorWET Sensor in substrate block


"As a progressive agriculture consultancy we've been using the WET Sensor in multiple Indian open-field and hydroponic research projects over the last two years. We've found the sensor to be very robust and easy to use - and the readings it provides to be extremely accurate and consistent. Having extensively tested the sensor across a number of agri-climatic zones, we can happily endorse this instrument as a high quality research tool - that is ideally suited to extreme conditions." Chetan V Dedhia
CVD Solutions
Mumbai, India
"Optimising the quality and yield of our fruit is a key priority for Clock House Farms. By knowing the exact EC and moisture levels hour by hour we have the data that enables us to react quickly to changing substrate conditions.

It is the immediacy of the data which the WET Sensor provides that is valuable to us, not just the excellent accuracy.

In terms of benefits that the WET Sensor provides, it not only gives us the confidence that we have optimal growing conditions at all times, it has also enabled us to reduce irrigation levels (whilst enhancing produce quality) - eliminating unnecessary water wastage and reducing expensive fertiliser costs."
Nick Deppe, Farm Manager
Clock House Farm, Kent, UK
"We have used the Delta-T Wet Sensor since its introduction. This device has allowed us to have precise control over the EC in our strawberry and raspberry substrate grown crops; delivering better quality, flavour and yields. We could not manage without this excellent tool now." Harriet Duncalfe
H&H Duncalfe, UK
"We've successfully integrated a large number of Delta-T Devices WET Sensors into our measurement systems. We use them continually - to provide EC, moisture and temperature measurements. This valuable data helps our customers to improve the yield and quality of commercial Cucumber and Tomato crops." Martin Drop
Hortitechnic, UK
  • Moisture and nutrient status in the root zone
  • Rapid monitoring of growing conditions
  • Calibrations for many soils and substrates

The WET Sensor has crucial applications in precision horticulture and soil science research and is usable in both soils and growing substrates. It is exceptional in its ability to measure pore water conductivity (ECp), the EC of the water that is available to the plant.

Video – The Wet Sensor’s use in commercial horticulture

Rapid checks on growing conditions

The sensor is easily inserted into substrates, composts and most soils. It takes less than 5 seconds to measure water content (%), pore water conductivity (ECp) and temperature – all being important indictors of root zone health.

Pore water conductivity

The WET Sensor is able to calculate pore water conductivity (ECp) which is the EC of the water available to plant roots. The ECp calculation is derived from an approximate relationship between dielectric properties. This applies particularly well to WET Sensor readings, which are taken at the same frequency within the same defined region of soil/substrate. The approximation is valid in most soils and is particularly accurate in mineral wool and other artificial substrates media.

Fertigation and hydroponics

Where plants are grown in artificial substrates using hydroponic or fertigation systems, nutrients are routinely supplied in irrigation water. Nutrient levels are controlled by monitoring the water content and conductivity (EC) and adjusting the injection of liquid fertiliser into the irrigation water. The Delta-T Devices WET Sensor excels in monitoring this crucial information.

Container-grown shrubs and trees

Nutrients are sometimes provided by fertigation but are often provided by Controlled Release Fertilisers (CRF). The rate at which these are taken up depends on several factors, including the weather conditions and irrigation regime.
The Delta-T Devices WET Sensor can be used to measure the EC within the growing media and so take much of the guesswork out of this process.

Soil salinity

If the irrigation water is recycled or abstracted from rivers and aquifers with high levels of dissolved salts, over time there can be a build up of soil salinity. Soil salinisation will eventually reduce crop yields. The WET Sensor is fast and efficient for sampling soil salinity, ensuring that farmers have the essential information they need to take remedial action as quickly as possible.


WET Sensors are normally ordered as a complete kit that includes a WET Sensor, an HH2 Moisture Meter and a handy carry case. There are three types of Kit – each with a different set of substrate calibrations. Please download our Soil Moisture Measurement catalogue for further details.

Readout and data logging

For portable applications, readout and data storage are handled by the HH2 Moisture Meter. Alternatively, the WET Sensor can be connected to the GP1 Data Logger or GP2 Data Logger and Controller, making it possible to monitor growing conditions over a period of hours, days or longer. The smart relay capability in these data loggers allows them to control water content in response to EC or temperature.

WET Sensors used aboard China’s Tiangong-2 Space Station

The WET Sensor has been used by Chinese astronauts to conduct horticultural experiments in space. find out more.

Soil and horticultural substrate calibrations

If the WET Sensor is purchased with an HH2 Moisture Meter (as part of the WET Kit) it will be equipped with calibrations for generic mineral soils, organic soils, sand soils, clay soils, coir (coco fibre), peat based potting mixes, greenhouse ‘mineral’ soils, and Stonewool artificial mineral wool substrate (vertical and horizontal measurement).

If the WET Sensor is used with a GP1 Logger or GP2 logger it will be equipped by default with calibrations for generic mineral soils, organic soils, sand soils and clay soils. Two additional calibration upgrade packs are available – one of which contains calibrations for coir (coco fibre), peat based potting mixes, and greenhouse mineral soils, and one which contains Stonewool artificial wool substrate (vertical and horizontal measurement). See the accessories section of this page for more details.










Measurementvolumetric water contentPore water conductivityTemperature
Accuracy± 0.03 m3.m-3 (3%) see graph below ± 1.5°C
Soil moisture measurement rangeFull accuracy over:
0 to 1 m3.m-3
see graph below 0 to 50°C
Salinity range0 to 300 mS.m-1
Supplied with extended range calibrations which should be used for readings between 300 to 500 mS.m-1
Temperature range-5 to 50°C
OutputSerial TTL data providing permittivity, bulk conductivity and temperature, from which water content and pore water conductivity are calculated
Power requirement6-10 V, ~38 mA for 2.5s
Sample volume~500 ml
Sample volume is weighted towards soil immediately surrounding the rods
Dimensions and weightOverall: 120 x 45 x 13 mm
Rods: 68 mm x 3 mm diameter
Outer rods 68mm x 3.0 mm dia
Central rod 65 mm x 5.0 mm dia
Weight: 0.1 kg
Sensor calibrationsSensor calibrations supplied in WET Sensor EEPROM
Recalibration advised every 3 years (dependent on use)
Soil calibrations

Generalised Mineral ,Organic, Sand and Clay calibrations are supplied, specialist calibrations are available for horticultural substrates (please enquire at sales@delta-t.co.uk for more information) .

Wet Sensor chart


Product Resources

Data Sheets

Case Studies




Technical Notes

Sensor Calibration File Locator

Input your 5 or 6 digit serial number below (do not include a slash or space) to download your WET Sensor calibration file. (Example: 28073 or 120055).

IMPORTANT: If your serial number only has 4 digits, for example 22/19 – please add a zero before the last two digits – i.e. 22019

The serial number can be found on the sensor’s blue cable label. Contact tech.support@delta-t.co.uk if your serial number is not recognised - and we will assist you directly.

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