If I use an ultrasonic sensor will it detect the water level?

I was thinking about a product to read water level on water boxes (common in Brazil). I researched about instrumentation for this measure, and I think that an ultrasonic sensor is the best option. Will the water correctly reflect ultrasound and not change the normal measurements against a solid obstacle?


Technology used in depth finder, in marine application is mostly like is the best to measure the water from the top.

To measure water level from the bottom of tank one could use a piezo electric ceramic transducer combined with an Analog Front End (AFE) and a micro-controller to measure water level. The diagram below best explains the configuration.

Fluid Level Sensing

You can use a piezo electric ceramic transducer from Steminc, TDC1000 AFE from Texas Instrument and a MSP430 micro-controller also from Texas Instrument. There might be other configurations, but currently I am only aware of this configuration.

Piezo Electric Transducer

Transducer 1 Transducer 2

Analog Front End (AFE)

Analog Frond End
Click on image for a larger version of the image.

Limitation: The thickness and material of the tank might be an issue. For the most part above configuration work with plastic.


  • $\begingroup$ Is AFE attached at the sides of the container? What if we want to attach sensors only at the bottom of tank? $\endgroup$ – Ankesh kumar Jaisansaria Mar 6 '17 at 8:36
  • $\begingroup$ @AnkeshkumarJaisansaria The AFE will be placed on a PCB board and packaged anywhere you want. The transducer can be attached the the bottom of the tank and wired to the AFE. $\endgroup$ – Mahendra Gunawardena Apr 5 '17 at 22:39


To answer your specific question, yes, you can use an ultrasonic sensor to measure fluid level. Mahendra's answer describes that. You mentioned that you feel that an ultrasonic sensor is the best solution, but I wanted to add make sure that you were aware of some of the other methods that are used to measure fluid levels.

Measuring Techniques

This list of fluid level measuring techniques comes from an appropriately named website, "A Dozen Ways to Measure Fluid Level and How They Work".

  • Sight Glass
  • Floats
  • Hydrostatic Devices
  • Bubblers
  • Load Cells
  • Strain Gauges
  • Magnetic Level Gauges
  • Capacitance Transmitters
  • Magnetostrictive Level Transmitters
  • Ultrasonic Level Transmitters
  • Laser Level Transmitters
  • Radar Level Transmitters

There is no need to repeat the details of how each of these methods work, but this is a comprehensive list of technologies that could be considered.

  • 1
    $\begingroup$ Talk about a timely post! I am in the middle of doing a project where we need to measure the column of water in a well casing, and we need to do it cheaply. Your link was dead on target. We just recently started looking at the Bubbler solution because it allows us to simply drop a tube (maybe 3/8") down the well, then pump until the pressure plateaus. The link validates this as a good approach. Question: do you know a source for cheap air pumps that can deliver 300kPa to 500kPa of pressure (100' to 150' of water) into a bubbler-type solution? $\endgroup$ – Peter Rowell May 14 '15 at 0:57

Or you could just buy one. They are used in oil industry to measure liquid level in wells. They are necessary to turn the pump jacks off /on.


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