Measurements: Deep Drainage


Monitor Groundwater Leaching, Drainage and Recharge

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.

Accurately Measure Drainage

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

Choose 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


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


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


Drainage: 0.2 mm

Water Depth: 0.5 mm

Electrical Conductivity: 0.001 dS/m

Temperature: 0.1°C


Drainage: +1.4 mm

Water Depth: +0.1 % of full scale @ 20 °C

Electrical Conductivity: +0.01 dS/m or + 10 % (whichever is greater)

Temperature: +1°C

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
SOLUTION COLLECTION SURFACE AREA 507 cm2 (25.4 cm inside diameter)

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 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
DATA LOGGER COMPATIBILITY (NOT EXCLUSIVE) Decagon Em50 Series, ProCheck, Campbell Scientific
SOFTWARE COMPATIBILITY ECH2O Utility (rev 1.64+), DataTrac3 (rev 3.4+)


PAN LYSIMETER Poor Medium - Large Low $ Flux divergence under unsaturated conditions
STATIC TENSION (WICK) LYSIMETER (I.E. DRAIN GAUGE) Fair Small - Medium Low $$ Mid range accuracy, mid range cost
CONTROLLED TENSION LYSIMETER Excellent Medium High $$$ Minimal flux divergence/convergence issues; new turn-key systems with lower maintenance
WEIGHING LYSIMETER Best Medium High $$$$$ Quantify and manipulate hydrology


Drain Gauge G3 AutoPump

When measuring deep drainage there are often times when there may be higher volumes of drainage. Because the Drain Gauge G3 captures all drainage in the measurement area, the sample reservoir often becomes full. If water is not removed from the resevoir before it collects 61 mm of drainage, water will come into contact with the wick. If this occurs, sample water can be pulled out of the reservoir due to capillary rise, resulting in an under estimation of deep drainage. 

We designed the AutoPump with these remote and high drainage sites in mind.  It automatically drains the Drain Gauge G3 reservoir into additional bottles on the surface for later collection or into the field at a point away from the measurement area. 

Drain Gauge Sensor

We recommend using the additional temperature, depth and conductivity DG Sensor to measure cumulative drainage. Without using the sensor, only manual measurements of cumulative drainage can be made with the Drain Gauge. This sensor will allow you to get the data you need, and know when it is time to take a sample from the reservoir. DG Sensors can be added as an accessory to new units or easily installed on G3 Drain Gauges already in the field.

Request Support

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