Fill level monitoring for containers, tanks and dispensers

Fill levels matter in many buildings, often without anyone measuring them regularly. Typical applications are:

• Dispensers in washrooms: soap and paper dispensers in schools, administrations and stores. The alert comes before a dispenser runs empty, not after a complaint.
• Waste and recycling containers: bins and containers are emptied when they are full instead of being collected half empty on a fixed schedule.
• Tanks for liquids: the tank level is measured without contact from above or through the tank wall, without anyone opening the lid.
• Cisterns, wells and basins: a submersible probe measures the water level at the bottom, in pump sumps too.

For bins and containers, a sensor measures the distance to the surface by laser or ultrasound; in wells and cisterns, a submersible probe measures the water level; for tanks, a sensor can also measure through the container wall. Which fill level sensors fit depends on the medium, container shape and mounting.

According to the data sheet, the EM400-TLD laser distance sensor measures between 2 and 350 cm, and the EM400-UDL ultrasonic level sensor measures liquid levels up to 10 m. The Dragino DDS20-LB is stuck under the container and measures up to 200 cm of liquid height through the wall, without drilling. The devices run on batteries and transmit via LoRaWAN.

In wells, cisterns and basins, a level sensor measures the water level via the pressure of the water column at the bottom. The EM500-SWL submersible probe is available for 0 to 3, 0 to 5 or 0 to 10 m of water column. The history shows how quickly a store fills or empties, for example after rain or during high consumption.

A rising sump level may indicate a fault. Combining water level, an existing pump fault contact and a leak sensor provides additional information for on-site investigation.

A clear threshold is often enough: nearly empty or nearly full. A figure in liters also needs the container shape, because volume does not always change evenly with height. The history also shows whether a container regularly runs out sooner than expected. In facility management, this leads to needs-based service routines.

You set the fill level alarm yourself: a lower threshold for refilling, an upper one for emptying, or both. The alert goes by SMS, email and to the dashboard for the responsible group, such as cleaning, the custodian or waste collection. With schedules you decide whether alerts are also sent at night and on weekends.

A distance sensor is mounted above the contents, usually on the lid or on a bracket above the opening. A clear view of the surface is important: edges, ladders or fittings in the measuring range distort the result. With submersible probes, the probe hangs at the bottom while the transmitter sits outside the water.

Battery-powered level sensors do not need a power connection at the container. Battery life depends on the model, measurement frequency, radio conditions and temperature. Plan battery replacements and regular functional checks. A configured offline rule flags when expected messages from a monitoring point stop arriving.

Fixed rounds mean that full containers are visited too late and half-empty ones unnecessarily. With measured fill levels, cleaning and waste services plan their routes according to actual demand. With many sites, the dashboard shows at a glance where something needs doing.

The stored histories also help with planning: where would a smaller container do, where is refilling needed more often, and on which days is use highest? Together with people counting, washroom cleaning can follow actual use.