ONSET HOBO U20-001-03 250-Foot Depth Water Level Data Logger

HOBO 250-Foot Depth Water Level Data Logger is ideal for recording water levels and temperatures in shallow wells, streams, lakes and freshwater wetlands.

  • Product Name:ONSET HOBO U20-001-03 250-Foot Depth Water Level Data Logger
  • Model:U20-001-03
  • Maunufactor:Onset
  • Country:USA


The HOBO water level data logger features high accuracy at a great price and ease-of-use, with no cumbersome vent tubes or desiccants to maintain. This data logger is ideal for recording water levels and temperatures in shallow wells, streams, lakes and freshwater wetlands.

Highlighted Features

  • Lightning protection - no long signal wires, and electronics are shielded in stainless steel housing for use in freshwater (see the Water Level logger sensor location drawing)

  • HOBOware Pro software provides easy conversion to accurate water level reading, fully compensated for barometric pressure (see demo) temperature, and water density.

  • Multiple-rate sampling (see demo) allows faster sampling at critical times such as when pumping starts or stops.

  • Available in 4 depth ranges

  • Ideal for use in wells, streams, lakes, wetlands and tidal areas

  • No-vent-tube design for easy reliable deployment

  • Available in stainless and titanium versions

  • Durable ceramic pressure sensor

  • 3-point NIST-traceable calibration certificate included

In what environment does this data logger operate?

This data logger operates in outdoor and underwater environments.

What measurements does this data logger support?

The U20-001-03 data logger supports the following measurements: Absolute Pressure, Barometric Pressure, Temperature and Water Level

Pressure and Water Level Measurements U20-001-03 and U20-001-03-Ti

Operation Range:0 to 850 kPa (0 to 123.3 psia); approximately 0 to 76.5 m (0 to 251 ft) of water depth at sea level, or 0 to 79.5 m (0 to 262 ft) of water at 3,000 m (10,000 ft) of altitude

Factory Calibrated Range:69 to 850 kPa (10 to 123.3 psia), 0° to 40°C (32° to 104°F)

Burst Pressure:1200 kPa (174 psia) or 112 m (368 ft) depth

Water Level Accuracy*:

Typical error: ±0.05% FS, 3.8 cm (0.125 ft) water

Maximum error: ±0.1% FS, 7.6 cm (0.25 ft) water

Raw Pressure Accuracy**:±0.3% FS, 2.55 kPa (0.37 psi) maximum error

Resolution:<0.085 kPa (0.012 psi), 0.87 cm (0.028 ft) water

Pressure Response Time (90%)***:<1 second; measurement accuracy also depends on temperature response time

Temperature Measurements (All Models)

Operation Range:-20° to 50°C (-4° to 122°F)

Accuracy:±0.44°C from 0° to 50°C (±0.79°F from 32° to 122°F), see Plot A in manual

Resolution:0.10°C at 25°C (0.18°F at 77°F), see Plot A in manual

Response Time (90%):5 minutes in water (typical)

Stability (Drift):0.1°C (0.18°F) per year


Real-time Clock:± 1 minute per month 0° to 50°C (32° to 122°F)

Battery:2/3 AA, 3.6 Volt lithium, factory-replaceable

Battery Life (Typical Use):5 years with 1 minute or greater logging interval

Memory (Non-volatile):64K bytes memory (approx. 21,700 pressure and temperature samples)


Stainless steel models: approximately 210 g (7.4 oz)

Titanium models: approximately 140 g (4.8 oz)

Dimensions:2.46 cm (0.97 inches) diameter, 15 cm (5.9 inches) length; mounting hole 6.3 mm (0.25 inches) diameter

Wetted Materials:316 stainless steel, Viton® o-rings, acetyl cap, ceramic sensor

Logging Interval:Fixed-rate or multiple logging intervals, with up to 8 user-defined logging intervals and durations; logging intervals from 1 second to 18 hours. Refer to the HOBOware software manual.

Launch Modes:Immediate start and delayed start

Offload Modes:Offload while logging; stop and offload

Battery Indication:Battery voltage can be viewed in status screen and optionally logged in datafile. Low battery indication in datafile.

Environmental Rating:IP68 

ce.jpg    The CE Marking identifies this product as complying with all relevant directives in the European Union (EU).

* Water Level Accuracy: With accurate reference water level measurement, known water density, accurate Barometric Compensation Assistant data, and a stable temperature environment.

** Raw Pressure Accuracy: Absolute pressure sensor accuracy includes all sensor drift, temperature, and hysteresis-induced errors.

*** Changes in Temperature: Allow 10 minutes in water to achieve full temperature compensation of the pressure sensor. Maximum error due to rapid thermal changes is approximately 0.5%.