Water Level Sensors



The OTT RLS offers a large measurement range with a small blanking distance and narrow beam width and it easily connects to most dataloggers. The RLS has extremely low power consumption and is ideal for remote or solar powered sites.

Application: Surface water
Parameters measured: Water level / distance to water
Measurement technology: Non-contact pulse radar
Product highlights: Measures water level or depth to water from a bridge, pier or mounting arm
Measurement range: 0.8 … 35 m
Accuracy: 0.8 … 2 m: ± 10 mm; 2 … 30 m: ± 3 mm; 30 … 35 m: ± 10 mm
Internal data logger: No
Interface: SDI-12, RS-485 (using SDI-12), or 4 …20 mA

  • No drift over time
  • High Performance–Measurements are unaffected by air temperature, humidity, flood events, floating debris, or contaminated water; reduces the likelihood of missing data and reduces data post processing
  • Low Maintenance–Flat antenna design eliminates nesting areas for insects and periodic maintenance requirement
  • Flexible Integration/Easy Setup–Connects to most data loggers via standard communication interfaces, SDI-12 or 4 … 20 mA; no need for additional PC software
  • Simple Installation–Light weight compact design facilitates easy mounting on bridges, extension mounting bracket or inside a small protective housing
  • Low Profile Design–Unobtrusive appearance is ideal for urban installation sites or sites prone to vandalism
  • Low Power Consumption–Ideal for remote or solar powered sites; requires only 12 mA when active


Water level measurements
Measuring range 0.8 … 35 m
Resolution SDI-12 output 0.001 m
Accuracy (SDI-12) 0.8 … 2.0 m: ±10 mm;

2.0 … 30 m: ±3 mm;

30 … 35 m: ±10 mm

Average temperature coefficient (-10?+40 °C) 0.01 % full scale/10 K
Accuracy (4?20 mA) ±0.1 % full scale
Average temperature coefficient 10 ppm full scale/°C (at 20 °C)
Measuring time 20 s
Beam angle of antenna (width of beam) 12 º
Electrical data
Power supply 9.6 … 28 V DC, typ. 12/24 V DC
Power Consumption In Active Mode < 140 mW (<12 mA bei 12 V)
Power consumption in rest mode < 1 mW (<0,05 mA bei 12 V)
Interfaces 4 … 20 mA, SDI-12, RS-485 (SDI-12 Protocol)
Housing ASA (UV-stabilized ABS)
Radom (front plate) TFM PTFE
Mounting bracket 1.4301 (V2A)
Lateral axis ±90 º
Longitudinal axis ±15 º
Dimensions and weight
Dimensions L x W x H
Weight (incl. mounting bracket) approx. 2.1 kg
Operating temperature: -40 … +60 °C
Storage temperature -40 … +85 °C
Relative humidity 0 … 100 %
Type of protection
With horizontal mounting IP67 (submersion depth max. 1 m; submersion duration max. 48 h)
EMV limits and radio approvals
EMV for low power radio devices ETSI EN 301 489-3
Low-voltage device safety EN 60950-1
  • RLS - Radar Level Sensor for Surface Water

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