The pressure testing has to be carried out using filtered potable water.
The water system must stay completely filled until taken into operation. The presence of remaining quantities of water in the piping greatly increases the danger of corrosion in metal piping (three phase corrosion).
If a water system is not used soon after the pressure testing, then the pressure testing should be carried out using compressed air or inert gases.
pressure testing water system
The pressure testing, flushing and start-up of the system have to be documented.