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HYDROS-21 3 in 1 Water Level Sensor

  • Model: E-240-40683
  • Manufactured by: Meter (formerly Decagon / UMS)

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Product Description:
A compact 3.4 cm diameter sensor that fits into tight spaces, the HYDROS 21 is a low-cost, durable, and easy-to-use tool for monitoring EC, temperature, and depth in both groundwater and surface water. More importantly, it’s an all-in-one instrument. When used with our EM60G data logger, you won’t require an additional sensor for determining—and correcting for—barometric pressure. With a range of 0 to 120 dS/m and a measuring depth of 10 m, the sensor makes accurate EC measurements for a broad range of applications.

  • Continuously monitor groundwater and surface water level changes
  • Integrated electrical conductivity and temperature measurement
  • 3.4 cm diameter sensor that fits into tight spaces
  • Low cost
  • Durable
  • Easy to use


Water depth: 0 to 10,000 mm 

Electrical conductivity: 0 to 120 dS/m

Temperature: -11 to 49 °C, do not expose to temperatures <32 °F if sensor is in wat


Water depth: 2 mm 

Electrical conductivity: 0.001 dS/m 

Temperature: 0.1 °C

AccuracyWater depth: +/- 0.05% of full scale @ 20 °C
Electrical conductivity: ±0.01 dS/m or ±10% (whichever is greater)
Temperature: ±1 °C
Operation temperature

0 to 50 °C (Pressure transducer cannot be allowed to freeze while submersed)

Power requirements3.6 - 15 VDC, 0.03 mA quiescent, 0.5 mA during 300 ms measurement

 9 cm (l) x 3.4 cm (w)

Measurement time 300 ms (milliseconds)
Output Serial TTL, 3.6 Volts Levels or SDI-12
Connector types

3.5 mm (stereo) plug or stripped & tinned lead wires (3)

Cable length 10 m standard; custom lengths available upon request
Software compatibility ECH2O Utility (rev 1.64+), DataTrac3 (rev 3.4+)