Cold Water Cistern Requirements

• Water Regulation Guide G16.13
• Protected Cistern By Law 30 Kit
• 350 mm - MIN space above cistern (maintenance puprpose)
• 25 mm - MIN height from bottom for side outlets (connections from the bottom of the cistern are preferred)
• 0.65 mm - MAX mesh size opening for Air Vent and Screen
• Should withstand 500 hours of boiling water
• Use Hole Saw ONLY to cut the holes for pipe connections
• 20°C - MAX temperature of stored cold water (25°C at outlets)
• Plastic Washer MUST be used for connections (Oil-based paste of any description should not be used)
• Made of:
  • Now: polyethylene, polypropylene, polyvinyl chloride
  • Past: galvanised low carbon steel
  • Produced in black to prevent Algae Growth

Base of the Cistern Requirements

• MUST be fully supported with Moisture Resistant 25 mm Chipboard approved by National House-Building Council
• 150 mm MIN overlap of a baseboard from each side
• 3 Timber Bearers required for a typical domestic cistern
  

Legionella Bacteria

• Document L8 - Guidance for the control of legionella bacteria in water systems
• Store water above 60°C or below 20°C
• The water in the taps should be below 20°C after 2 minutes

Sizing

• 115L  - MIN size of CWSC or at least equal to HWSC (for direct systems)
• 230L - recommended by BS 6700 for for indirect systems or = 2 x HWSC (if it also supplies a feed to a hot water cylinder)
• 230L – MIN size of CWSC (for industrial installations)
• 80L – per bedroom
• 130L per bedroom (refilling at night)

Overflow Pipe

• Must be screened
• MIN Ø19mm
• MIN Ø25mm for CWSC >1000L
• MIN termination - 25mm above water line
  • 50mm if CWSC capacity is > 1000L
• Should be always greater in size than Feed Pipe
• NO flexible parts
• MUST be separate with F&E overflow pipe
• Separate Warning Pipe is fitted 25mm below Overflow Pipe for CWSC > 1000L

Byelaw 30 Type Kit

• Dip Tube - 50mm "Dipped Feed"
• Screened warning pipe elbow