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

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