SC Plug

Temporary Water Diverting Method for Drainage Facilities

The SC plug method is a temporary water diverting method that allows liquid waste to drain naturally. An SC (water cutoff) plug together with a bypass pipe are installed through the drainage channel. This method allows the inside of the drainage facility to dry out, creating a safe and hygienic work environment. No external pipe is necessary so the work space needed is compact, and impact on the surrounding environment can be kept to a minimum.

New civil engineering technologyMarch 2018 Japan Institute of Wastewater Engineering and Technology


  • design that produces a tight water seal. A hollow rubber washer set round the outside of the plug is tightened by a bolt so that the hollow rubber is compressed and fastens tightly to the pipe.

  • The water cutoff plug and bypass pipe can be taken separately through a manhole opening (φ600mm), so no existing structure needs to be demolished and even a large-diameter pipe can be accommodated.
  • The mechanical adhesion design means there is no risk of liquid waste leaking from a total interruption of flow, and the arrangement can be left for long periods in a dry condition.
  • The plug and bypass pipe can be assembled and installed without stopping flow of liquid waste.
  • Previously, work was undertaken in a poor environment due to hydrogen sulfide gas, bacteria and viruses, but drying out creates a better working environment and boosts efficiency.
  • With natural flow drainage there is no pumping up to external pipes, and no maintenance is needed over long periods of installation.
  • The all-purpose plug can be used with all existing pipe designs: circular, rectangular or other.

Actual mouth sizes:
Circular: 200mm to 3,750mm diameter
Rectangular: 350 x 350mm to 2,400 x 3,580mm

Installation Method

1 Manhole repair

2 Manhole creation