We've had some water pressure issues due to construction. Apparently, since our valves are pretty old, due to them being opened and closed so many times in the last weeks, we may have disturbed the sediment or even jeopardized the quality of the valves, including the pressure reducing valve. Sigh. I just started seeing dollar signs.
Luckily, after a thorough investigation, it turns out that was not the problem. Thank God. The air that was in the pipes actually detached supply lines to some of the toilets, which in turned had for a result low water levels. The plumber reattached them back, and, yes, I'll say this again, thank God, we didn't have to fiddle with the main valves any more. Phew.