BDT Level Alarm

BDT Blocked Sewer Alarm Transmitter

The BDT Blocked Sewer Alarm is the most popular dielectric based sewer and drainage alarm on the market and has now clocked up 10-years of service and is available with either a 10 or 20-year plus battery life. Compatible with existing buildings BMS & SCADA and our latest IoT+ Dashboard.

Used by:

  • Utilities – Water & Wastewater
  • Drain Contractors
  • Local Authorities
  • Healthcare inc the UK’s NHS
  • Hotels & Hospitality
  • Schools
  • Offices
  • Heavy Industry
  • Food Production, Agriculture & Farming
  • Domestic

Sewers and drains block for a variety of reasons ranging from sewer collapse, tree roots through to the build up of FOG and wet wipes, etc. sewers and drains in critical location require monitoring 24/7. The frequency of blockages tends to increase significantly where there are kitchens, public toilets and in particular baby change facilities. Early warnings of a blockage can be invaluable to businesses as they permit them to avoid spills and contamination. It also allows them to plan maintenance out of hours, in private and out of sight of customers.

The British designed and manufactured BDT is an award winning and industry proven level monitoring device that has been specifically designed for sewer and drain monitoring. BDTs are normally installed underneath existing manhole covers in areas at risk from blockages. Wireless technology makes BDT installation easy, with minimal disruption and without the need for cables.

BDT Blocked Sewer Transducer MKI

BDT Blocked Sewer Transducer MKI, first Introduced in 2010

The is a proven with a 10-year track record, and is an alternative to using ultrasonics for real-time blockage and surcharge detection in sewers, storm drains, tanks and wet wells. Unlike ultrasonic transducers which are difficult to programme and consume vast amounts of energy and cannot be used in confined spaces, the BDT is easy to use as it does not require programming. Further, the energy required is just 1/50,000 compared to that of as typical the ultrasonic or its more modern microwave radar counterpart.

Bulk Dielectric Transducers [BDT] Technology has no moving parts, is easy to install often without the need for confined space entry teams. Normally supplied with a wireless transmitting head unit the BDT plus its radio can enjoy a battery life of up 10-years in spite of broadcasting data every 2.5 seconds. The BDT is ideal for drive-by monitoring or fixed networks where messages can be delivered to existing SCADA, remote data servers or interfaced with BMS/telemetry over distances of many km using our Network Boosters, Gateway Receivers or Cellular Data Concentrators.

The BDT can also be used as a flood alarm. In this application it has many advantages as there are no moving parts to become snagged by spiders webs of debris, further the BDT self tests and reports positive if covered in debris, whereas ultrasonics simply fail and go blind. In flood applications the BDT can be interfaced with a variety of radio systems enabling communication over distances of up to 25km or its status can be relayed over the cellular or Iridium satellite network.

 Areas of Use:

  • Detecting Blockages in Sewers
  • Wet Well High Alarms
  • Sewer Surcharge Monitoring
  • Storm Drain Monitoring
  • Industrial & Commercial Sewer Alarms
  • Basement Flooding Alarm
  • Community Flood Alarms
BDT installation from the surface without confined space entry

BDT installation from the surface without confined space entry

Key Features:

  • Proven Long Service Live
  • Set Point from 0.3m to 4.5m (10m optional) depth
  • IP68 100% submersible design 10 year battery life
  • Green HDPE injection moulded transducer housing
  • Real-time 2.5 or 30 second read and transmission rate
  • 10 or 20+ year battery life
  • No field programming or software required
  • Installed from surface to eliminate the need and cost of confined space entry
  • ATEX certified Zone 2
  • Licence Free: EN-300-220,  Radio Equipment Directive [RED]
  • Compatible with RDNET1000TM Boosters and Receivers to extend range to up to 5Km from the manhole
  • Supplied with stainless steel mounting bracket
  • Set point simple to set by curling cable
  • Receiver options include: Gateway with relays to telemetry or SCADA, IP Gateways, handheld patrol receiver or PC:,
  • Options of radio interfaces to EN-300-113 and FCC-Part 90.

Data Sheet:

For a full data sheet click here: BDT Level Transducer Issue 2.0

BDT blocked sewer system

BDT blocked sewer alarm transducer installed to detect sewer surcharges


The BDT MKII was introduced in the summer of 2014, featuring a brand new injection mounded housing in water repellent HEDP and enhanced immunity to FOG and ragging. The MKII BDT is fully compatible with existing Gateway Receivers and Booster/Repeaters.

ATEX Zone 2 Approved

ATEX Zone 2 Approved

The MKII BDT has  has already been installed in hundreds of locations both in the Utility and Industrial / Commercial sectors.