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Cold Water

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

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Water Contamination

Fluid Categories

Water Regs Schedule 1

  • defines categories of fluids
  • Blue Water – corrosion of copper caused by stagnation
  • Air Gap = which is greater: 20mm or 2 x inlet Ø (MIN 25 mm for the bath)
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Category 1

  • wholesome water to Schedule 67 of the Water Industry Act 1991
  • water supplied from the Water Undertakers
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Category 3

  • low toxicity;
  • slight health hazard (showers, bathes, washbasins; hose with shut-off control, domestic heating system; WC cistern)
  • Prevention: EC/ED - Double Check Valve (Verifiable/None-verifiable; reed more); HUK1; CA;
  • Air Gaps: AG; AUK1(back-siphonage 5); AUK2;
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Category 4

  • toxic substances;
  • significant health hazard (non domestic heating, anti-freeze, mini-irrigation systems, permeable hoses, fire sprinkler with additives)
  • Prevention: BA - Reduced Pressure Zone Valve (RPZ; reed more)
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Category 5

  • Serious health hazard (WC pan, bidet bowl, human and animal waste, laboratories, medical)
  • Prevention: Air Gap Only!
  • Air Gaps: AA; AB; AUK3; DC;
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