Hydrant monitoring at Skanderborg Forsyningsvirksomhed A/S

AVK brought old hydrants back to life by supplying new retrofitted hydrant covers with an integrated sensor and a communication system.

Skanderborg Forsyningsvirksomhed has been facing an ongoing issue concerning the usage of its hydrants, and it contacted AVK asking for an application to reveal when the hydrant cover is opened. The reason is that Skanderborg Forsyningsvirksomhed for some time now has suspected that some of its hydrants have been exposed to water theft and used to flush tanks of vacuum trucks, but it hasn´t had a system to neither confirm nor deny its suspicion.


To limit the risk of contaminating the clean water supply, Skanderborg Forsyningsvirksomhed first needs to ensure that all vacuum trucks empty the tank in the correct location. Secondly, that they only flush the tank using a designated hydrant at Skanderborg Forsyningsvirksomhed’s premises. 

Skanderborg Forsyningsvirksomhed has a license plate recognition system which scans all license plates of vehicles going in and out of their premises. Combining the information of when the hydrant cover is opened and closed, with who is on site at that time can reveal which truck driver is using the designated hydrant correctly, and who isn’t.

Besides the risk of contamination, draining water through a hydrant for other purposes than fire protection is theft and leads to an increased amount of non-revenue water.


When Skanderborg Forsyningsvirksomhed contacted AVK, it asked for an application which was retrofitable, battery powered, and communicating by using Sigfox protocol (radio communication) to show the position of the hydrant cover, and would be nonvisible when the hydrant cover is closed.

The development of the application was handled by ACMO, which is the latest AVK acquisition and excels in the development of applications like this. 


Besides the specifications mentioned, a big challenge was to find a solution which could be mounted on the inside of the hydrant cover and still stay within the mechanical boundaries.

The solution is a fully encapsulated product which is mounted directly on the inside of the hydrant cover and holding an integrated battery (with 10 years lifetime), antenna, accelerometer and electrical board. The accelerometer is sensing the gravitational force at any time. This means that when the hydrant cover is opened, the accelerometer is sensing a change in the relative gravitational force which is leading to an alarm message. 

The communication from the hydrant is sent via a Sigfox-concentrator to Skanderborg Forsyningsvirksomhed’s SCADA-system. This enables monitoring of the hydrant cover position and battery condition and seeing historical data of the hydrant position. 

In the near future, Skanderborg Forsyningsvirksomhed believes that it will be able to reveal if someone is misusing the hydrants as suspected.

At the end of the day, the monitoring ensures a continuous supply of clean and healthy water to the consumers, ensures the lowest possible risk of contamination of water and trying to avoid theft. 

Skanderborg Forsyningsvirksomhed A/S

Skanderborg Forsyningsvirksomhed A/S is the main supplier of water in the municipality of Skanderborg with a population of approx. 62,000 inhabitants. It is furthermore responsible for all wastewater treatment in the municipality. 

The AVK premises in Galten, Skovby and Låsby are located in the municipality of Skanderborg. 

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