- July 24, 2025
Choosing the Right Submersible Level Transmitter for Your Water or Wastewater Applications
A submersible level transmitter is a pressure-based sensor designed to be fully immersed in a liquid. It measures the hydrostatic pressure exerted by the liquid column above it and converts this pressure into an electrical signal that corresponds to the liquid level.
- Groundwater wells
- Lift stations
- Stormwater and wastewater tanks
- Industrial water treatment systems
- Environmental monitoring and irrigation systems
Their ability to provide continuous, real-time level data makes them indispensable in both municipal and industrial settings.
In water and wastewater management, accurate level measurement is critical for ensuring system efficiency, safety, and compliance. Whether you’re monitoring groundwater levels, managing stormwater tanks, or operating a wastewater treatment plant, selecting the right submersible level transmitter can make a significant difference in performance and reliability.
Why Choosing the Right Transmitter Matters
Choosing the wrong transmitter can lead to inaccurate readings, frequent maintenance, or even system failure. The right transmitter, on the other hand, ensures:
- Accurate level monitoring
- Reduced downtime
- Lower maintenance costs
- Improved system control and automation
Consideration Factors when Choosing Submersible Level Transmitter for Water or Wastewater Applications
- Application Environment
Understanding the environment where the transmitter will be deployed is the first step. Ask yourself:
- Is the liquid clean water, wastewater, or chemically aggressive?
- Will the sensor be exposed to sludge, debris, or high solids?
- What are the minimum and maximum operating temperatures?
For example, wastewater applications often involve liquids that are chemically aggressive, abrasive, or contain high levels of suspended solids, making them potentially corrosive to standard sensor materials. These sensors should have clog-resistant designs, such as flush diaphragms or non-fouling coatings, to prevent sensor failure or inaccurate readings due to biofilm or sludge buildup.
In contrast, clean water systems, such as those used in drinking water treatment or reservoir monitoring, typically handle fluids with minimal contaminants. In these applications, the priority shifts to high measurement accuracy, long-term signal stability, and minimal drift over time.
- Material Compatibility
When selecting a level or pressure sensor, it is critical to ensure that the sensor’s wetted materials, the parts in contact with the media, are chemically compatible with the process fluid. Incompatible materials can lead to corrosion, pitting, swelling, or degradation, which can compromise sensor accuracy and lifespan.
Different environments demand different materials:
- Stainless Steel (SS316L): A widely used material in water treatment due to its good corrosion resistance and durability. It is well-suited for clean water applications and some mild wastewater conditions, but it may not withstand high chloride content or highly acidic or alkaline media.
- Titanium: Offers excellent corrosion resistance, especially in saline or brackish water, industrial wastewater, or marine environments. It is ideal when chloride levels are high or when long-term reliability is essential in harsh media.
- Hastelloy or Teflon-coated sensors: These are used in aggressive chemical environments, such as industrial effluents, caustic wash-down areas, or chemical dosing systems. Hastelloy C-22, for example, provides exceptional resistance to a broad range of corrosive substances, including oxidizing and reducing agents. Teflon (PTFE) coatings are useful for applications requiring non-stick, chemically inert surfaces.
Selecting the correct material not only prevents sensor failure but also reduces maintenance frequency and extends operational life, especially critical in difficult-to-access installations such as lift stations, chemical tanks, or submerged pipelines.
- Measurement Range
It is essential to select a pressure or level transmitter with a measurement range that closely matches the actual depth of your application. This ensures accurate, high-resolution readings and avoids performance issues.
For example:
- Shallow tanks: Typically require sensors with a range of 0–5 meters
- Deep wells or boreholes: May need sensors with ranges up to 0–100 meters or more
Using a sensor with a much larger range than necessary (e.g., a 0–100 m sensor in a 2 m tank) can result in poor resolution and low measurement sensitivity, especially for small level changes. This is because the output signal (typically 4–20 mA or 0–10 V) is spread across a much wider span, so small changes in level cause only tiny changes in output, making it harder for the system to detect and respond accurately.
Conversely, using a sensor with a range that’s too low (e.g., a 0–2 m sensor in a 5 m tank) can lead to sensor overrange or damage, and result in incorrect or unstable readings.
For optimal performance:
- Always match the sensor range to your actual level range.
- Where possible, choose a range that slightly exceeds the maximum expected level to allow for surge or overflow conditions, but not so much that it sacrifices accuracy.
Proper range selection enhances both data reliability and system control efficiency in level monitoring applications.
- Accuracy and Resolution Specification
Accuracy and resolution are critical performance metrics when selecting a level or pressure transmitter, especially in high-stakes applications such as chemical dosing, flow billing, or environmental monitoring, where even small errors can lead to regulatory non-compliance or financial loss.
- Accuracy refers to how close the sensor’s reading is to the actual level or pressure. It is typically expressed as a percentage of the full-scale (FS) range. For example, a sensor with ±0.25% FS accuracy on a 10 m range can have up to ±25 mm potential deviation.
- Common accuracy classes include:
- ±0.25% FS: for critical applications
- ±0.5% FS: industrial standard
- ±1.0% FS: general monitoring
- Common accuracy classes include:
- Resolution is the smallest change in level or pressure that the sensor can detect. Even if a sensor is highly accurate, poor resolution can limit its ability to track small but meaningful fluctuations, which is particularly important in applications like tank level management, leak detection, or precision blending.
In critical applications or environments with fluctuating temperatures, it’s recommended to choose sensors with built-in temperature compensation. This feature corrects for temperature-induced errors in real-time, ensuring that measurement accuracy is maintained across varying ambient and fluid conditions.
When evaluating sensor specifications, always consider:
- How the accuracy and resolution align with your process control requirements
- Whether environmental conditions (e.g., outdoor tanks or warm effluent) could affect performance
- If the transmitter outputs are stable enough to be integrated into automated control systems
- Output Signal Type
Select a transmitter with an output signal compatible with your control system and installation environment:
- Analog outputs (4–20 mA or 0–10 V):
- 4–20 mA is preferred for long-distance transmission, as it is less affected by voltage drop over extended cable runs.
- 0–10 V is suitable for shorter distances but can lose accuracy due to voltage loss over long cables.
- Both are widely used in PLCs, SCADA systems, and industrial automation for their simplicity and reliability.
- Digital outputs (RS485, Modbus, SDI-12):
Best suited for networked installations, data logging, and remote monitoring. Digital signals offer multi-variable data, diagnostics, and the ability to connect multiple sensors on a single bus.
Use 4–20 mA for long cable runs, and digital outputs when advanced communication or diagnostics are needed.
- Certifications and Compliance
Depending on your industry, you may need transmitters that meet specific standards:
- IP68 rating: Rated for complete protection against dust and water, including full submersion.
- ATEX or IECEx: For hazardous environments
Always verify that the transmitter complies with local and industry-specific regulations.
Choosing the right submersible level transmitter is not just about picking a sensor, it’s about ensuring the long-term success of your water or wastewater system. By considering factors like media compatibility, measurement range, accuracy, and output type, you can select a transmitter that delivers reliable performance in even the harshest environments.
Need Help Selecting the Right Sensor?
At MeasureX Australia, we offer a wide range of high-performance submersible level transmitters tailored for both water and wastewater applications. Whether you need a rugged sensor for a lift station or a high-accuracy model for groundwater monitoring, our specialist team are here to help.
Our Highlighted Models:
- MRL21 Submersible Level Transmitter is a compact submersible level transmitter with a rugged SS316L or Tantalum diaphragm, ideal for clean or mildly aggressive liquids in confined spaces. It offers high accuracy (up to 0.1% FS) and reliable performance in long-term submerged applications.
- MRL23 Submersible Level Transmitter for Sewage Applications and Corrosive Environment features a PVDF housing and ceramic diaphragm, making it perfect for corrosive and sewage environments with chemicals like hydrochloric or nitric acid, while maintaining high precision and IP68 protection.
- MRL24 Submersible Level Transmitter with Integrated Temperature Sensor is a submersible level transmitter with an integrated temperature sensor, enabling simultaneous monitoring of liquid level and temperature. Built with a durable SS316L or Tantalum diaphragm, it offers high accuracy and long-term stability in harsh environments. Ideal for applications requiring dual-parameter measurement with compact IP68-rated construction.
Contact us today to speak with a specialist and we’ll help you to select or customise the best solution for your application.
