Water sensors

Water detectors are used to detect leaks. They serve to prevent transmission breakdown in telecommunication facilities, seepage from service or waste water in the earth or ground water pollution due to leakage of chemical substances.

If a leak occurs, the water detectors cause measurable attenuation changes as a result of manufacturer-dependent macrobending loss in the fibre.

44.1 WS-B/K1

Bending-insensitive fibres:

44.2 WS-G

Bending-sensitive fibres:


  • The water detector (optical sensor E9/125 ITU-T G.652) detects and pinpoints the source of water or chemicals leaks in closed cable joint boxes or water collecting tanks.
  • An optical fibre is selected and inserted into optical sensor E9/125 for monitoring purposes. This may be done subsequently to the initial installation without any interruption of on-going processes.
  • The optical sensor works on the basis that single mode optical fibres acc. to ITU-T G.652 or ITU T G.657 are bending-sensitive.
  • As soon as the target medium is detected, the optical sensor causes bending in the monitoring fibre, with a measurable increase of attenuation.
  • Regular control checks of the route should be carried out at least once a month, to detect any deviation in relation to the reference measurements taken when the route was inspected for acceptance.
  • This enables early detection of any increase of attenuation (e.g. alert given by the activated sensor) or other optical events.
  • If the sensor has been activated, the cause of the problem can be dealt with and attenuation returns to normal.
  • For networks with bending-insensitive optical fibres acc. to ITU-T G.652.D and ITU-T G.657.A, active fibres may also be used for monitoring purposes.