Tank Level Sensors: Types, Installation, and Monitoring

Water tanks are in almost every facility: rooftop tanks, ground tanks, raw water reservoirs at plants, chemical tanks, and irrigation tanks on farms. As long as there is water, nobody thinks about them. Problems only show when a tank runs dry mid-shift, a pump runs dry until it breaks, or water overflows for hours without anyone knowing.

A water tank level sensor answers one simple question continuously: how full is the tank right now? This article covers the sensor types, how to install them correctly, and how to use the data to prevent problems.

Common level sensor types

• Float switch. Cheap and simple, but it only tells you whether water is above or below one point. Good for triggering a pump, not for knowing tank contents.
• Ultrasonic. Mounted above the tank, it measures the distance to the water surface from reflected sound waves. It never touches the water and suits clean water and many other liquids.
• Hydrostatic pressure. Submerged at the tank bottom, it reads the pressure of the water column above. Stable in deep tanks and unaffected by foam or vapour at the surface.
• Radar. Similar to ultrasonic but using radio waves, more tolerant of vapour and temperature, and usually more expensive.

From water height to volume

The sensor reads height or distance, while what you usually want is volume. For rectangular tanks or upright cylinders, volume is directly proportional to water height. For horizontal cylinders or irregular tanks the relationship is not linear, so a conversion table is needed. That is why tank dimensions should be recorded correctly at installation.

Showing tank contents in both percent and litres helps two audiences: operators only need the percentage, while purchasing or planning needs litres.

Installing for accurate readings

1. Keep away from the inflow. Water falling from the inlet pipe churns the surface and makes ultrasonic readings jump.
2. Mind the blind zone. Ultrasonic sensors have a minimum distance below the sensor face that cannot be measured. Mount with enough clearance above the highest water level.
3. Avoid obstructions such as ladders, pipes, or supports in the beam path.
4. Calibrate empty and full points with one manual measurement at installation.
5. Protect from heat and rain for outdoor tanks.

Using level data

• Low-level alarms before the tank is actually empty, with enough time to act.
• High-level alarms to prevent overflow when a float or valve sticks.
• Pump protection, stopping the pump when the source level is too low so it never runs dry.
• Daily usage patterns, showing when water use peaks and how long a full tank lasts.
• Leak detection: a level that keeps falling at night when nothing is being used points to a leak in the tank or pipes.

Automating pumps from level data

Once level is read reliably, pumps can run on data: switching on when the level falls below the lower limit and off when it reaches the upper limit. With a platform that supports actuator control and automation rules, this logic can be set from the dashboard and changed at any time, without rewiring the pump panel. The history is recorded too, showing how often the pump runs and how long each cycle lasts.

Example: how long will the tank last?

An illustration: a 10,000-litre tank is 60% full, or 6,000 litres. Usage data from recent days shows an average of 500 litres per hour during working hours. So without refilling, the tank lasts about 12 working hours. Figures like this help facility teams decide when to start the fill pump or order water from outside, well before the tank runs dry.

The same calculation can appear automatically on the dashboard as an estimated time remaining, so operators do not have to work it out.

Not just for water

The same principle applies to other tanks: water treatment chemicals, generator fuel, or liquid raw materials in a plant. For specific liquids, choose a sensor whose materials resist that liquid and that meets the area's safety standards, especially for flammable substances.

Frequently asked questions

Which sensor suits a clean water tank best?

Ultrasonic is a common choice because it never touches the water and is easy to install. For deep or foamy tanks, a hydrostatic pressure sensor is often more stable.

Can we monitor many tanks at different sites?

Yes. Every sensor sends data to the same platform, so all tanks appear on one dashboard.

Can a level sensor switch a pump on?

Yes, through automation rules and actuator control. Keep local pump protection in place as a safeguard if the connection drops.

Monitoring tanks with INCLUDE

The IncludeBox Water Level Tank sensor reads water height and shows tank percentage and volume on the INCLUDE platform. Low and high level alarms can be set per tank, and pumps can be controlled through automation rules. Third-party level sensors can also connect via Modbus and IncludeGateways, or directly over MQTT and HTTP.