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Cold Water

Exam revision materials for Plumbing Level 2&3 and ACS Gas Safety test

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Installation Requirements


Soundness Test

  • BS 6700 - requirements for testing copper/plastic pipework

  • Testing non-plastic pipes
    • the installation shall be pumped up to 1.5 times the normal working pressure
    • the test shell be for 1 hour
    • during this there should be no visible leaks and no loss of pressure

  • Testing systems containing plastic pipes
    • Test A
      • Pumping for 30 minutes and pressure is noted
      • the pressure is reduced to one third of the test pressure
      • the pressure does not drop over the following 90 minutes
      • there is no visible leaks through out the test
    • Test B
      • Pumping for 30 minutes and pressure is noted
      • the drop in pressure is less than 0.6 Bar (60kPa) after a further 30 minutes
      • and less than 0.2 Bar after the next 120 minutes
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Flushing and Disinfection

  • Every new water service should be thoroughly flushed with drinking water
  • Drinking Water Inspectorate - approves the chemicals used to disinfect
    • EN 900 - Calcium Hypochlorite
    • EN 901 - Sodium Hypochlorite
Disinfection Applies to:
  • new installations (except private dwellings occupied by a single family)
  • major extensions or alterations (except private dwellings occupied by a single family)
  • underground pipework (except localised repairs or insertion of junction for 50mm underground pipes [BS 6700])
  • where contamination may be suspected
  • after physical entry by personnel for interior inspection, painting or repairs
  • where a system has no been in regular use and not regularly flushed (over 30 days)
Disinfection recommendations
  • Where pipework is under mains pressure, or has a backflow device fitted downstream, the water undertaker should be notified
  • If water used for disinfection is to be discharged to a sewer, drain or water course the authority responsible for the sewer, drain or course should be notified
  • Chemicals used for disinfection of drinking-water installations must be chosen from a list of substances complied by the drinking-water inspectorate, which is listed in the Water Fittings and Materials Directory published by the WRAS (sodium hypochlorite can be used)
Safety factors
  • The system must be taken out of use, marking all outlets 'Do Not Use DISINFECTION IN PROGRESS'
  • All operatives carrying out the disinfection must receive appropriate Health and Safety training under the COSHH Regulations
  • No other chemicals should be added to the water during disinfection (could generate toxic fumes)
  • All occupants within the premises must be notified that disinfection is taking place
The procedure for disinfection
  • Thoroughly flush the system
  • Introduce a disinfection agent at specified concentration into the system
    • If using chlorine use initial concentrations of 50 mg/litre
  • leave the system for a contract period of 1 hour.
    • if using chlorine, check the free residual chlorine levels at the end of the contract period
    • if this is less than 30 mg/litre, then procedure requires repeating
  • Immediately following successful disinfection, the system should be drained and thoroughly flushed with clean water until the residual chlorine level is at the same level as the drinking water supplied
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