Hot and Cold Water Pipes Sizing

Recommended dimensions of hot and cold water pipes

The table below can be used to determine the maximum numbers of draw offs served by a pipe:

Nominal bore of pipeMaximum number of draw offs served
Flow pipesReturn pipes
inSteel pipe
(mm)
Copper pipe
(mm)
Head up to
20 m
(70 ft)
Head over
20 m
(70 ft)
1/2 15 15 1 1 - 2 1 - 8
3/4 20 22 2 - 4 3 - 9 9 - 29
1 25 28 5 - 8 10 - 19 30 - 66
1 1/4 32 35 9 - 24 20 - 49 67 - 169
1 1/2 40 42 25 - 49 50 - 79 170 - 350
2 50 54 50 - 99 80 - 153
2 1/2 65 67 100 - 200 154 - 300
  • Basins, sinks, showers and similar are regarded as 1 draw off
  • Baths and similar are regarded as 2 draw offs

Related Topics

  • Water Systems - Hot and cold water service systems - design properties, capacities, sizing and more

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