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Testing and Commissioning Method Statement For Drainage System

Below is the step wise procedure for Testing and Commissioning Method Statement For Drainage System

Instruments & Tools required:

  • Valve operating keys.
  • Measuring Stick
  • Plumbing Toolkit

Work Sequence / Commissioning Phases


Pre-Commissioning: System Pre-Commissioning Checks

Before commissioning the system the following shall be ensured.

  • The Installation and Leak testing of the pipes are completed.
  • The installations sanitary wares (WC, Wash Basin, etc.) are completed.
  • The sanitary wares are properly operating.

Commissioning Phase: Commissioning Checks for Drainage System

  • Complete installation of Drainage system as per the approved drawings & method statement of installation.
  • Complete leak testing for all the floors & the risers as per method statement for testing, and hand over all leaks testing to consultant & contractor.

Performance Test

  • Check all sanitary wares by discharging individually and by group; it should drain speedily, quietly and completely.
  • Check the Floor drain/trap water seal by dip stick or small diameter transparent tube, a minimum of 25 mm of water seal should be retained in every trap.
  • Repeat above test three (3) times with the trap or traps being recharged before each test.

Tests for self-siphonage and induced siphonage in branch discharge pipes

  • To test for the effect of self-siphonage the sanitary wares (wash basin, sink, and bath tub) should be filled to overflowing level and discharged by removing the plug; WC pans should be flushed.
  • Measure the seal remaining in the trap when the discharge has finished.
  • Ranges of Sanitary wares, connected to a common discharge pipe, should also be tested for induced siphonage in a similar way.
  • Refer to number of sanitary wares that should be discharged together.
  • Measure the seal remaining in all the traps at the end of the discharge. Note: The worst conditions usually occur when the sanitary wares at the upstream end of the discharge pipe are discharged.

Test for induced siphonage and back pressure in discharge stacks

  • Discharge simultaneously a selection of Sanitary wares (WC, wash Basin) connected to the stack.
  • Check & monitor the trap and seal losses due to positive or negative pressures in the stack.

Note: These selected sanitary wares should normally be close to the top of the stack and on adjacent floors, as this gives the worst pressure conditions. The baths are ignored as their use is spread over a relatively long period and consequently they do not add materially to the normal peak flow. Where a stack serves baths only, the number to be discharged simultaneously in a test should be taken to be the same as for sinks. Flows from showers are small and these can usually be ignored for stacks serving mixed Sanitary wares. Similarly for non-domestic buildings, spray tap basins and urinals need not be included in the test when the stack also serves other sanitary wares.


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