U20-001-04 water level data logger for recording water level and temperature

Ideal for use in wells, streams, lakes, wetlands, and tidal areas. With its narrow range, this logger provides the best accuracy in shallow waters. A great value and easy deployment with no cumbersome vent tubes or desiccants to maintain.

U20 Water Level Logger without vent tube for shallow water

HOBO U20-001-04 Water Level Data Logger

U20-001-04 data logger records water level and temperature up to 13-ft (4m) water depths in wells, streams, lakes and freshwater wetlands. This logger provides the best accuracy in shallow waters with it's narrow range. A great value and easy deployment with no cumbersome vent tubes or desiccants to maintain. For saltwater deployments, such as brackish wetlands and tidal areas, HOBO U20 Water Level Titanium model is available. To learn more, please contact us.

HOBO Optic USB Base Station or HOBO Waterproof Shuttle is required for configuration and data offloading data from the data logger.

Highlighted Features

• Lightning protection - no long signal wires, and electronics are shielded in stainless-steel housing for use in freshwater
• HOBOware Pro software provides easy conversion to accurate water level reading, fully compensated for barometric pressure, temperature, and water density
• Multiple-rate sampling allows faster sampling at critical times such as when pumping starts or stops
• Water level and temperature at depths of up to 13, 30, or 100 feet in a wide range of underwater environments; for use in freshwater or saltwater
• 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

Pressure and Water Level Measurements U20-001-04 and U20-001-04-Ti

 Operation Range

Factory Calibrated Range

Burst Pressure

Water Level Accuracy*

Raw Pressure Accuracy**


Pressure Response Time (90%)***

0 to 145 kPa (0 to 21 psia); approximately 0 to 4 m (0 to 13 ft) of water depth at sea level

69 to 145 kPa (10 to 21 psia), 0° to 40°C (32° to 104°F)

310 kPa (45 psia) or 18 m (60 ft) depth

Typical error: ±0.075% FS, 0.3 cm (0.01 ft) water. Maximum error: ±0.15% FS, 0.6 cm (0.02 ft) water

±0.3% FS, 0.43 kPa (0.063 psi) maximum error

<0.014 kPa (0.002 psi), 0.14 cm (0.005 ft) water

<1 second; measurement accuracy also depends on temperature response time

Temperature Measurements (All Models)
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 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

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

Important Info
Requires HOBOware Pro software and either a U-DTW-1 Waterproof Shuttle or the Base-U-4 Optic USB Base Station for configuration and data offload.

* 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%.