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Water Level Sensors 2017-10-17T15:30:01+00:00

Water Level Sensors

Water level, stage, or flow can be measured with many types of sensors: pressure transducers, bubblers, shaft encoders, or ultrasonic sensors. Your location, the accuracy required, and the ease of installation all contribute to determining the best water-level sensor for your measurement site. We can also build you a custom stilling well to house your water level monitoring system. Key components of our water level measurement systems are dataloggers, sensors, and communications devices, which can be customized for each site.

Greyline Instruments offers complete systems for monitoring water levels and monitoring flows in pipes.

Pressure Transducer or Vibrating Wire Piezometer

There are hundreds of transducer type sensors in the market today. There are a few things that set them apart. Most of these type of sensors use pressure on a thin wafer type sensor to measure the depth of water or even the pressure of the air. The other main sensor type is called a vibrating wire piezometer. This sensor uses a tiny wire and measures the vibration frequency of the wire when plucked by the sensor. The depth of the water changes the frequency of the wire.

Built-in Dataloggers

Some of the pressure sensors available have a built-in datalogger and these are often used in ground water monitoring due to their small form factor and ease of use and installation. We sell and support the Campbell Scientific CRS451/CRS456 water level and temperature dataloggers, and the Onset HOBO Water Level Loggers. These sensors have built-in dataloggers and are easy to deploy for measuring water levels in a variety of applications.

Datalogger and Sensor Integration

By combining a pressure transducer or vibrating wire sensor with one of the Campbell Scientific dataloggers you can create a rugged and flexible water level monitoring system. The CR200X series, CR300, CR800 series, and CR1000 dataloggers can read many different types of outputs and offer reliable data collection and can be implemented as a control system or warning system in many types of applications.

There are many sensors available here are a few we recommend. Contact us if you need something else; we can generally match what you are seeking.

CRS451 / CRS456

CRS451 / CRS456



  1. HOBO MX2001 Water Level Logger – Includes datalogger, built-in barometric compensation, and Bluetooth readout
  2. Acculevel Pressure Transducer – No internal datalogger
  3. CS451 Pressure Transducer – No internal datalogger
  4. CRS451 Water Level & Temperature Recording Sensor – Includes internal datalogger
  5. Onset HOBO Water Level Loggers – Includes internal datalogger

Ultrasonic Sensor

The SD100 ultrasonic depth sensor is an inexpensive solution for remotely measuring snow depth or water levels. The sensor works by measuring the time required for an ultrasonic pulse to travel to and from a target surface. An integrated temperature probe with solar radiation shield, provides an air temperature measurement for properly compensating the distance measured. An embedded microcontroller calculates a temperature compensated distance and performs an error checking routine.

Both distance and air temperature are output as an analog signal between 0 to 2.5 volts or 0 to 5 volts. Measurements can also be output digitally as serial ASCII. Specify Analog or Digital output at time order.

Due to the simplified interface, the depth sensor can interface with any datalogger or control system that can delay at least 3 seconds after powering up before measuring the output.

SD100 Brochure

SD100 Ultrasonic distance sensor

SD100 Ultrasonic

Bubbler Sensor

The OTT-CBS is a compact bubbler that generally measures ground or surface water level, but can also measure any liquid level. This bubbler has an accuracy of ±0.02 ft. A Campbell Scientific datalogger controls the OTT-CBS pump and calculates the measurements. The bubbler typically communicates with the datalogger via the SDI-12 protocol, which is supported by many dataloggers.

OTT-CBS Benefits

  • Ideal for areas where submersed sensors can be damaged due to corrosion, contamination, flood-related debris, lightning, or vandalism
  • Compatible with most Campbell Scientific dataloggers
  • Easy to maintain
  • Robust pump design provides reliable operation
  • Consistent accuracy ensured by drift-free measurements and offset compensation using relative measurement
  • Purge function clears the measuring tube and the bubble chamber of contamination
  • Does not use pressurized nitrogen tank—requiring less frequent attendance
  • Existing tubes can be used
OTT-CBS Brochure

CS470 / CS471 Bubbler SensorOTT-CBS

Radar Level Sensor

The CS475 is a radar-ranging sensor that monitors water level of rivers, lakes, tidal seas, and reservoirs. It can measure distances up to 20 meters. The CS475 outputs a digital SDI-12 signal to indicate distance and stage.

The CS476 can measure distances up to 30 meters.

CS475/476 Benefits

  • Ideal for areas where submersed sensors can be damaged due to corrosion, contamination, flood-related debris, lightning, or vandalism
  • Compatible with most Campbell Scientific dataloggers
  • Low maintenance—no moving parts significantly reduces maintenance cost and time
  • Low power consumption
  • Rugged enough for harsh environments—NEMA rated 4X
  • No FCC license required
  • Wide operating temperature range (-40° to + 80° C)
CS475 Brochure

CS475-L Radar Level Sensor

Shaft Encoder Float & Pulley

Shaft encoders are known for their ease of use and ruggedness. They are not affected by frozen water and are easy to calibrate. Shaft encoders are very popular in open channel and canal type irrigation systems. The USGS use shaft encoders in hundreds if not thousands of locations across the USA.

The WaterLOG® H-3311 is a digital shaft encoder, which measures water level by monitoring the position of a float and pulley. This unit outputs SDI-12 and 2-wire Quadrature. The H-3311 is easy to use and works with any SDI-12 data recorder. The shaft encoder is generally more accurate than a potentiometer system and will not wear out over time like a potentiometer. We have sold WaterLOG® units for many years and have found them to be of high quality with the ability to provide many years of service. This specific model has an LCD display and can be calibrated without moving the shaft and pulley.

H-3311 Brochure

H3311 Shaft Encoder


Custom Built Stilling Wells – Corrugated Steel or PVC

We can build any type of stilling well for your water level measuring project. We build stilling wells out of steel corrugated pipe and PVC products.

We can supply nearly any diameter, but we have some standard sizes that we recommend.

  • 8″ Corrugated Steel
  • 12″ Corrugated Steel
  • 24″ Corrugated Steel
  • 36″ Corrugated Steel
  • 12″ PVC Pipe
  • 24″ PVC Pipe

All of our still wells come with a 3/4″ or 1″ access coupler or nipple at the bottom of the well, this allows you to attach a PVC or steel pipe to the well for water access. All of our wells also come with a shelf or flange(s) at the top for attaching a cabinet or enclosure. If you would like we can also provide the cabinet or enclosure based upon your requirements.

Stilling well stream guage system

Above is an example of a USGS type stream Gage system. Most often a simple corrugated pipe and cabinet are now installed for low cost and ease of use.

Corrugated Steel Stilling Well

Shaft Encoders and Float & Pulley type sensors are the most commonly used sensor in this setup, however, an ultrasonic or pressure sensor can easily be adapted to a stilling well application.

Stilling well cabinet