Most of our machines have a steam/hot water tap/valve.

If I can offer one piece of advice to ensure a long life for these often neglected facilities on our espresso machines it would be, Don't turn them off murder tight all they need to seal should be a gentle tighten, a bit like locking in a portafilter, if you have to use brute force you have a problem that needs addressing, no need at all to wring the chickens neck, if the tap/valve does not seal easily its probably time for a little home or professional maintenance, most of them are pretty simple to work on and repair.