Solinst Model 201 Water Level and Temperature Meter
The Solinst Model 201 Water Level Temperature (WLT) Meter combines manual depth-to-water measurement with temperature profiling in wells, boreholes, tanks, and open water. Temperature appears on the reel-mounted LCD, while water level and probe depth are read from the laser-marked flat tape.
Choose an imperial configuration from 100 to 1,000 ft or a metric configuration from 30 to 300 m using the options on this page. The 201 is suitable for groundwater monitoring, temperature profiling, geothermal investigations, and studies of changing thermal conditions.
Measure Water Level and Profile Temperature
When the probe’s detection point reaches conductive water, a light and buzzer activate. Read the tape at your reference point to determine depth to water. To build a temperature profile, lower the probe to selected depths and record each depth with its stabilized temperature reading.
The buzzer can be muted while profiling temperature, allowing the operator to take submerged measurements without a continuous audible signal. The water-contact indicator light remains active.
The 201 is a manual instrument. It does not automatically record readings, calculate drawdown, or provide an unattended time series.
Temperature Range and Accuracy
The temperature measurement range is -20°C to +125°C. Manufacturer-stated accuracy is ±0.10°C from -5°C to +50°C and ±0.50°C outside that interval, within the specified measurement range.
The display resolves temperature in 0.01°C increments. Display resolution is separate from measurement accuracy and should not be interpreted as ±0.01°C accuracy.
For the best temperature accuracy, fully submerge the probe and allow the reading to stabilize at each measurement depth. Solinst specifies a temperature stabilization time of approximately 15 seconds per degree Celsius of temperature change.
Submersible Probe and Laser-Marked Flat Tape
The 16 mm (5/8 in) diameter probe has a 316 stainless steel body and a protective sensor shroud. It is pressure-proof and submersible to the full length of the meter’s tape. This rating applies to the probe, not the reel.
The 10 mm (3/8 in) wide PVDF flat tape has permanent laser markings every 1/100 ft on imperial LM2 configurations or every millimeter on metric LM3 configurations. Graduation spacing describes the distance between markings and is separate from overall depth measurement accuracy.
Check probe clearance along the entire access path before deployment, including restrictions around installed pumps, tubing, and fittings.
Portable Field Operation
The reel includes an LCD, carrying handle, probe holder, brake, accessible battery drawer, and tape guide. A standard 9V alkaline battery provides approximately 90 hours of use. The electronics include an automatic shutoff feature to conserve battery power.
No user temperature calibration is required. Routine equipment checks, cleaning, and proper measurement technique remain important for reliable field readings.
Applications for the Solinst 201 WLT Meter
- Manual depth-to-water measurements
- Temperature profiling in wells, boreholes, tanks, and open water
- Investigating thermal changes associated with runoff or inflow
- Geothermal drilling and temperature studies
- Comparing temperature conditions at selected depths and monitoring locations
The 201 measures water level and temperature. It does not measure conductivity, dissolved oxygen, salinity, or individual contaminants, and its readings alone do not establish drinking water safety.
Contact Activated Carbon Depot for help selecting tape length, measurement units, or quantities for your monitoring project.
Solinst Model 201 Technical Specifications
| Specification | Details |
|---|---|
| Measurement functions | Manual depth-to-water measurement and temperature profiling |
| Water level indication | Light and buzzer activate when the probe detects conductive water |
| Depth measurement | Read manually from the graduated tape |
| Temperature display | Reel-mounted LCD |
| Temperature measurement range | -20°C to +125°C |
| Temperature accuracy: -5°C to +50°C | ±0.10°C |
| Temperature accuracy outside -5°C to +50°C | ±0.50°C within the specified measurement range |
| Temperature resolution | 0.01°C |
| Temperature stabilization time | Approximately 15 seconds per °C of temperature change |
| User temperature calibration | Not required |
| Probe dimensions | 16 mm diameter × 129 mm long (5/8 in × 5.08 in) |
| Probe weight | Approximately 87 g (3.07 oz) |
| Probe submergence | Submersible to the full length of the meter’s tape |
| Tape material and width | Laser-marked PVDF flat tape, 10 mm (3/8 in) wide |
| Imperial graduations | LM2: feet and tenths, with markings every 1/100 ft |
| Metric graduations | LM3: meters and centimeters, with markings every millimeter |
| Imperial lengths listed on this page | 100, 200, 300, 500, 750, and 1,000 ft |
| Metric lengths listed on this page | 30, 60, 100, 150, 250, and 300 m |
| Wetted materials | PVDF, Santoprene, Delrin, Viton, and 316 stainless steel |
| Power supply | 9V alkaline battery |
| Battery life | Approximately 90 hours of use |
| Automatic shutoff | Eight-minute automatic shutoff; press the button to resume measurement if the display turns off |
| Automatic data logging | No; readings are recorded manually |
Temperature resolution, temperature accuracy, and tape graduation spacing describe different characteristics. Fully submerge the probe and allow readings to stabilize for the best temperature accuracy. Keep the reel above water.
Available Solinst 201 Models and Part Numbers
All configurations listed below measure water level and temperature. Select your required tape length and measurement units before ordering.
LM2 Imperial Models — Feet
| Tape Length | Configuration | Solinst Part Number / SKU |
|---|---|---|
| 100 ft | 201 WLT / LM2 | 113362 |
| 200 ft | 201 WLT / LM2 | 113364 |
| 300 ft | 201 WLT / LM2 | 113365 |
| 500 ft | 201 WLT / LM2 | 113414 |
| 750 ft | 201 WLT / LM2 | 113416 |
| 1,000 ft | 201 WLT / LM2 | 113418 |
LM3 Metric Models — Meters
| Tape Length | Configuration | Solinst Part Number / SKU |
|---|---|---|
| 30 m | 201 WLT / LM3 | 113366 |
| 60 m | 201 WLT / LM3 | 113367 |
| 100 m | 201 WLT / LM3 | 113368 |
| 150 m | 201 WLT / LM3 | 113413 |
| 250 m | 201 WLT / LM3 | 113415 |
| 300 m | 201 WLT / LM3 | 113417 |
Before Ordering
- Choose a tape length that reaches your deepest planned profiling position, rather than only the current water surface.
- Select LM2 imperial or LM3 metric tape to match your reporting procedures.
- Confirm clearance for the 16 mm diameter probe along the entire access path.
- Review the temperature range and applicable accuracy band for your measurement conditions.
- Match the selected configuration and part number to your purchase order.
Solinst’s broader 201 product family includes lengths up to 600 m (2,000 ft). The selectable configurations on this page extend to 300 m or 1,000 ft. Contact Activated Carbon Depot to confirm availability and pricing for requirements beyond the listed options.
Solinst 201 vs. 107 TLC and Standard Water Level Meters
| Model | Measurement Functions | When to Choose It |
|---|---|---|
| Solinst 201 WLT | Manual depth to water and temperature profiling | When you need water level and temperature readings without conductivity measurement |
| Solinst 107 TLC | Manual depth to water, temperature, and conductivity profiling | When your procedure also requires specific conductance readings |
| Solinst 101 P7 | Manual depth to water | When depth-to-water measurements are sufficient and you prefer laser-marked flat tape with a P7 probe |
| Solinst 102 P10 | Manual depth to water | When restricted access calls for a smaller 10 mm probe and narrow coaxial cable |
| Solinst 101D | Manual depth to water and selectable drawdown threshold detection | When you need an alarm as falling water exposes a probe positioned at a selected depth |
What Is the Main Difference Between the 201 and 107?
The 201 measures water level and temperature. The 107 adds conductivity measurement. Their temperature specifications also differ: the 201 measures from -20°C to +125°C, while the 107 measures from -15°C to +50°C. Compare the accuracy requirements and measurement conditions for your project before selecting a meter.
Do You Need Automatic Recording?
The meters compared here require manual recording of water level readings. The 201 also requires manual recording of its displayed temperature. For unattended measurements over time, select a suitable datalogger separately.
What’s Included with the Solinst 201 WLT Meter?
- Assembled Solinst Model 201 Water Level Temperature Meter with reel, probe, and selected tape length and measurement units
- 9V battery
- Tape guide
Sold Separately
A carrying case is sold separately and is not included with the meter. Replacement parts and additional accessories are also sold separately unless explicitly listed in your order.
Confirm your selected tape length, imperial or metric graduations, and Solinst part number before ordering.
Solinst 201 WLT Meter PDF Downloads
- Solinst Model 201 Water Level Temperature Meter Data Sheet (PDF) — Features, specifications, applications, and configuration information.
- Solinst Model 201 Operating Instructions (PDF) — Equipment checks, water level and temperature measurements, cleaning, and troubleshooting.
Follow the operating instructions applicable to your meter. Review the probe immersion, stabilization, and tape-guide procedures before taking field measurements.
Solinst 201 Water Level and Temperature Meter FAQs
The Solinst 201 measures depth to water and temperature. Temperature appears on the LCD, while water level and probe depth are read manually from the graduated tape.
No. The LCD displays temperature. Read water level and probe depth from the tape at your established measurement reference point.
The temperature measurement range is -20°C to +125°C. Check that your application conditions also meet the manufacturer's operating requirements for the equipment.
Solinst specifies ±0.10°C from -5°C to +50°C and ±0.50°C outside that interval, within the meter's -20°C to +125°C measurement range.
No. Resolution describes the display increment. The temperature accuracy is ±0.10°C or ±0.50°C, depending on the measurement temperature.
Yes, for the best temperature accuracy. Solinst recommends fully submerging the probe because its body affects temperature equilibration. Allow the reading to stabilize before recording it.
Solinst specifies approximately 15 seconds per degree Celsius of temperature change. Follow the operating instructions and wait for a stable reading at each profiling depth.
Yes. Press the button twice quickly to mute the buzzer. The indicator light remains active. Press the button twice quickly again to reactivate the buzzer.
No. The 201 measures water level and temperature. Choose the Solinst 107 TLC Meter if your procedure also requires conductivity. Dissolved oxygen requires separate suitable equipment.
No user temperature calibration is required. Perform the recommended equipment checks and follow the cleaning and maintenance instructions.
The probe is 16 mm (5/8 in) in diameter and 129 mm (5.08 in) long. Confirm that it can pass through the entire access path, including restrictions around installed equipment.
Yes. The probe is submersible to the full length of the meter's tape. This rating does not apply to the reel, which must remain above water.
Imperial models are available in 100, 200, 300, 500, 750, and 1,000 ft lengths. Metric models are available in 30, 60, 100, 150, 250, and 300 m lengths.
Ways to Contact Us
Activated Carbon Depot
Email: sales@activatedcarbondepot.com
Phone: 949-229-2587
