Table Provides Volumes for 1 meter length of pipe. Allow an extra 10% for fittings.

Material and Nominal Size Volume of 1m length Material and Nominal Size Volume of 1m length
Stainless Steel and Steel   MDPE SDR11  
15mm ½ '' 0.00024 20mm 0.00019
20mm ¾'' 0.00046 25mm 0.00033
25mm 1'' 0.00064 32mm 0.00053
32mm 1¼'' 0.0011 55mm 0.0016
40mm 1½'' 0.0015 63mm 0.0021
50mm 2'' 0.0024 75mm 0.0029
65mm 2½'' 0.0038 90mm 0.004
80mm 3'' 0.0054 125mm 0.008
100mm 4'' 0.009 180mm 0.017
125mm 5'' 0.014    
150mm 6'' 0.02    
Copper   MDPE SDR 17  
15mm 0.00014 90mm 0.005
22mm 0.00032 125mm 0.01
28mm 0.00054 180mm 0.02
35mm 0.00084    
42mm 0.0012    
54mm 0.0021    
67mm 0.0033