Decagon G3 Drain Gage

Lysimeter– wick lysimeter

The Decagon G3 Drain Gage is a wick lysimeter for the accurate measurement of near surface drainage in the vadose zone. The G3 Drain Gage is typically installed beneath the root zone for drainage measurements but it can also be installed in other locations. Therefore, the G3 wick lysimeter is not only ideal for hydrology studies, but it can also be used for nutrient leaching studies.

Advantages of the G3 Drain Gage wick lysimeter include:

  • Manual or automated measurements
  • Connect to data loggers with remote download and alarms
  • Simultaneous measurements of drainage, temperature and electrical conductivity (EC)
  • EC measurements can be used to estimate soil nutrient leaching


further information

Use the Drain Gauge to determine the volume of water and chemicals draining from the vadose zone into groundwater. Once installed, water samples are easily collected through the surface port for analysis of chemicals, fertilizers, and other contaminants. The Drain Gauge is constructed from inert materials and will not react with compounds collected in the sample reservoir.

One challenge with lysimeter measurements is that water can flow around receptacles buried in the ground. To correct for this, our Drain Gauge uses an ingenious duct and wick design to keep soil tension in the soil column similar to that of the natural soil at the installation site.

customize your drain gauge

Wick LysimeterChoose from a stainless steel or PVC divergence tube. Stainless steel is recommended for taking an intact soil monolith, but is not recommended for heavy metal testing.

For most applications we recommend using the additional Drain Gauge Sensor to measure conductivity, temperature, depth, and to help determine when to empty the sample reservoir. For installation sites that are remote or have high drainage rates, we recommend using the AutoPump to take samples or empty the reservoir automatically. The sensor and AutoPump can be easily integrated with pre-installed units and are ideal for use with a cellular data logger.

  • Completely sealed system protects from high water tables
  • 61 mm drainage capacity allows for large sampling volumes
  • Can be used with the optional EC sensor to monitor solute fluxes
  • Can be used with the optional AutoPump to automatically draw samples on remote or high drainage deployments


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feature specification
Dimensions Total Length: 147 cm DCT length: 63.5 cm DCT (Inside) Diameter: 25.4 cm Reservoir Length: 81.3 cm Reservoir (outside) Diameter: 11.5 cm Access Tube Length: 180 cm standard, customizable Access Tube, Outside Diameteter: 6.0 cm (2" schedule 40 PVC) Sample Evacuation Tube: 1.27 cm OD X 0.79 cm ID X 3 m length; custom lenghts available upon request Mass: 20 kg with Stainless Steel DCT, 14 kg with PVC DCT
measurement range
Drainage 0-61 mm bottom of wick and 61-100 mm top of reservoir chamber
Water Depth 0 to 3.5 m
Electrical Conductivity 0 to 120 dS/m
Temperature -11 to 49°C
measurement resolution
Drainage 0.2 mm
Water Depth 0.5 mm
Electrical Conductivity 0.001 dS/m
Temperature 0.1°C
measurement accuracy
Drainage 1.4 mm
Depth 0.1 % of full scale @ 20 °C
Electrical Conductivity 0.01 dS/m or + 10 % (whichever is greater)
Temperature 1°C
general specifications
Suction at Intake 110 cm (11 kPa)
Solution Collection Capacity 3.1 L (6.1 cm of drainage) to bottom of wick. Additional 5.1 L (10 cm of drainage) of reserve capacity in wick chamber
Collection Surface Area 507 cm2 (25.4 cm inside diameter)
Wetted Material DCT (standard): 304 Stainless Steel 11 gauge DCT (optional intert material): PVC Wick: dry fired fiberglass Root Inhibitor: Treflan (BioBarrierTM), removable Sample Evacuation Tube: Polyethylene Hydraulic Bridge Material: Diatomaceous Earth (DE) All Other Parts: PVC
Operating Temperature 0 to 50°C (Pressure transducer cannot be allowed to freeze while submersed.)
Power Requirements 3.6 - 15 VDC, 0.03 mA quiescent, 0.5 mA during 300 ms measurement
Measurement Time 300 ms (milliseconds)
Output SDI-12
Cable Length 10 m standard; custom lengths available upon request
Data Logger Compatibility Any SDI-12 data logger