The BTS Industries Group has designed a program to calculate size of PEX/Al/PERT pipes to facilitate the calculation process in water supply systems. Choosing the right pipe size in water supply systems is important due to inappropriate pipe sizes can disrupt user comfort in addition to increasing fixed and variable costs. This program, taking into account a wide variety of consumers, calculate the appropriate pipe size needed to feed them. The program also provides the SFU of a consumable unit, such as a toilet, bathroom, kitchen, etc., according to amount of SFU for each consumer. To determine the amount of SFU, many tables have been presented that the 16th chapter of the national building regulations has provided to the engineers with a complete set of them.