Cold water

• Domestic cold water systems


  Types of domestic cold water systems
• The Water Regulations (1999)


  National law for England and Wales covering waste, undue consumption, misuse, contamination and erroneous measurement of water

  
• WRAS


  Water Regulation Advisory Scheme

  
• BS6700


  Standard for design, installation, testing and maintenance of domestic cold water systems
• WRAS approved fittings


  Comply with The Water Regulations, are a legal requirement in the UK, are a quality product, corrosion resistant, and made of materials that do not cause contamination

  
• Cold water distribution


  1. Evaporation

  2. Condensation

  3. Precipitation

  4. Transportation

  5. Infiltration

  6. Run off
• Plumbers have a responsibility to design, install, test and maintain cold water systems correctly, and advise customers on good usage
• Surface water sources


  • Lakes
  • Reservoirs
  • Rivers
  • Streams
• Ardleigh Reservoir


  • Developed after a 1963 report on the expanding population of North East Essex
  • Raw water taken from the River Colne
  • Ferric Sulphate added to reduce phosphate levels
  • Covers 57 hectares and holds 2200 million litres when full
  • Draw off tower at deepest point draws water from 3 different levels
  • Air pumps turn the water over to prevent layers of different quality and temperature forming
• Water treatment process


  1. Screening to remove fish and unwanted matter

  2. Ferric Sulphate added to reduce phosphate levels

  3. Sludge drawn off

  4. Water disinfected with ozone gas

  5. Filtration through granular activated carbon and sand filters

  6. pH adjustment and chlorine added

  7. Sulphur dioxide added to reduce chlorine levels
• Mains distribution system


  • 600mm main divided into smaller pipes (100, 63, 50, 32 or 25mm) serving particular areas
  • Pipes used to be cast iron but now MDPE (medium density polyethylene)
  • MDPE pipes generally fusion welded with some compression fittings
  • Screwdown ferrule connector or service union installed allowing valve to be opened or closed with a ferrule key
• Underground water sources


  • Wells (deep, shallow, artesian)
  • Boreholes
  • Springs
• Hard water


  Contains calcium sulphates or limestone, hardness cannot be removed by boiling
• Temporary hard water


  Contains calcium carbonates, hardness removed when heated to 65°C
• Soft water


  Free from calcium carbonates and sulphates, either naturally soft or produced by a water softener
• Water hardness classifications


  • Soft (0-3.5 degrees Clark, 0-50 ppm CaCO3)
  • Moderately soft (3.5-7.0 degrees Clark, 50-100 ppm CaCO3)
  • Slightly hard (7.0-10.5 degrees Clark, 100-150 ppm CaCO3)
  • Moderately hard (10.5-14.0 degrees Clark, 150-200 ppm CaCO3)
  • Hard (14.0-21.0 degrees Clark, 200-300 ppm CaCO3)
  • Very hard (over 21.0 degrees Clark, over 300 ppm CaCO3)
• pH scale


  Indicates whether water is acidic or alkaline, below 7 is acidic and aggressive towards pipework
• Plumbers must be aware of the type and quality of water supplied to any property as this could affect the appliances within the property
• Under The Water Regulations, plumbers have a responsibility to maintain the quality of water supplied by the water undertaker, avoiding contamination