The BDT Sewer Alarm Celibrates its 15th Birthday

The BDT Sewer Alarm System was invented by Radio Data Networks 15-years ago. Since then has become the most widely deployed wireless sewer alarm ever, used by the facilities management (FM) departments of the NHS, public utilities, schools, industry, commercial buildings, shopping malls, agriculture and across the hospitality sector. In fact, anywhere where there is a risk of a sewer or drain becoming blocked and causing damage. BDTs will also report incidents of sewer flooding or surcharge from utility networks. As we write, it is estimated that every day our BDTs collectively send over half a million messages concerning the level of sewers and drains, confirming if they are normal or high.

A typical installation comprises of one or several BDTs mounted in access chambers inside or outside a building. These report back to a nearby receiver which is used to raise the alarm. For small buildings, domestic properties, hotels and schools, we have the Sentinel Receiver. The Sentinel generates a local audible alarm and includes status LEDs for up to four BDTs. For larger businesses with BMS systems there is what we call a BMS Gateway that translates messages from the BDT into an OK or Blocked message that is fed into the BMS system. These can accept messages from up to 8-BDTs. Since 2024 there has also been a cloud monitoring option where the status of the sewer can be monitored on a smartphone, tablet or desktop 24/7 with the option of email or text  warnings too.

What makes the BDT special and multi-award winning is its electronic high-level detection technique, which is totally solid-state with no moving parts to get snagged on debris and poo, hybridised with our RDNET1000 data protocol to send messages wirelessly, eliminating the need to chop up floors and to run cabled for the installation. Making the BDT what is often termed a Smart Sensor.

BDTs are always supplied ready to go 100% factory tested, with batteries sealed in for life and supplied with a stainless-steel wall bracket. The BDT is also certified safe to ATEX/UKEx Zone 2 against the risk of sewer gas and can withstand total submersion for days should the chamber completely flood.

Installation is simple as they can be safely installed from the surface without need to climb in the drains or sewer with the associated H&S risks. The trigger/alarm depth is simply set by curling up the cable and tying with a cable tie, testing and then the installation is complete. Typically, 5-minutes is all that is required. The receivers are best located near the chamber being monitored, but if this is not possible, we have a range of battery or mains powered repeaters that can extend the range of the signal. Again, these can be installed without software or programming in a matter of minutes.

The BDT is failsafe too, as unlike any other system is sends health check every 2.5 seconds to the receiver. This message contains the status of the BDT and omission of this message for a period of time will also raise an alarm.