BDT Level Alarm

Blocked Sewer Alarm – High Sump Alarm – The Award Winning BDT

Blocked Sewer and High Sewer Level detection and sump pump monitoring made easy! The BDT is simple to install proven technology that can deliver real-time Blocked Sewer / High Sewer Level Alarms, High Level Sump Alarm messages without cables to existing alarm panels, BMS, SCADA, or over a Wide Area Network to Mission Critical IoT and via Satellite SBD messaging services. 

The BDT is a unique and innovative born in the UK and the brainchild of RDN’s flounder Mr Brian M Back. Since its debut in 2010 the BDT has won multiple industry awards, numerous compliments  and deployments can be counted in their thousands.

Unlike float switches that can get held down by FOG, rags or wet wipes etc the BDT is fail safe. Because the system that is designed to detect high levels using a bulk dielectric transducer principle, thus will fail safe if fouled, ragged or held down by rags.

However, unlike other dielectric based sensors on the market, the BDT has been optimised to be operated for up to a decade on a single battery pack. It is also 100% water proof, includes an integrated wireless transmitter head and is declared for conformity to ATEX Zone 2 to mitigate the risk of explosion due to sewer gases, etc. that can occasionally build up in sewers and sumps.

Blocked Sewer Alarm System Installed

Blocked Sewer Alarm System Installed in London Restaurant

Simple to Install:

The BDT is supplied with 2m or 4m of cable which separates the BDT Transducer and the Transmitter Head Unit. The head unit is normally mounted from the surface just below the manhole of the sewer or sump cover and secured in place using stainless steel screws. The cable is then tied up to set the depth of the transducer and hence the trigger point and the job is compete.

Key Features:

  • Proven and award winning technology backed with almost 10-years of service history.
  • Up to 2m or 4m set depth
  • No Moving Parts
  • Sealed for life 10 year lithium battery
  • ATEX Zone 2
  • 100% waterproof design to > IP68
  • No software or programming require
  • 2-year warranty against battery failure
  • Stainless steel mounting brackets


  • Blocked Sewer Alarm
  • Sewer Surcharge Alarm
  • Sewer Flooding Alarm
  • Blocked Sump Pump Alarm
  • High Wet Well / Sump Alarm
  • Flooded Basement Alarm
  • Blocked Drain Alarm
  • Blocked Culvert Alarm

Receiver Options:

  • Gateway Receiver – Connects to existing BMS, SCADA or Telemetry
  • Sentinel Wall Mounted Receiver – Alarm panel style receiver with LEDs and sounder in stainless steel enclosure
  • Solar Assisted Beacon Receiver – Outdoor receiver for industrial and commercial applications with flashing beacon
  • Beacon Receiver – Indoor / outdoor battery powered receiver with Beacon to warn of blockages.
  • Satellite Gateway to report data globally via LEO Satellite Networks
  • Mission Critical IoT Gateways including PMR, DMR and Tetra

Repeater Options:

  • Wide Area Network Booster / repeater – Relays the messages over distances of up to 5km (version dependant) – battery powered
  • Local repeater – relays message locally up to 200m – mains powered

Sales & orders

Please call your local distributor for prices on products, systems and solutions. Spares and accessories may also be purchased through our online web portal