My mom got a handyman to repair a faucet and she turned the basement main water supply valve on and off a couple of times. The last time I hear a loud swish and there's a dripping or tapping sounds from the HVAC system. She didn't take any additional steps like bleeding or keeping a faucet on or doing it slowly when turning on or off the supply.
Is it possible or likely a pipe burst when it came back on?
The exact thing happened to a neighbor when they were having the final inspection on the condo they sold!
The water was off and the Realtor turned it back on from the outside shutoff.
The downstairs neighbor was sitting in his Livingroom and heard "his shower running". When he went to investigate he saw water running out of the can light over his tub. he went to the upstairs unit to see what they were doing and the people in there had no idea anything was wrong. They only heard a rumbling noise in a wall of the bathroom when they went to investigate.
What happened was a CPVC fitting was never glued and came apart with the sudden pressure spike of the water turning on. So what happened in your mother's house is not uncommon. Investigation will be needed to find the issue, ( weak pipe, bad connection, etc.) This in no way would be your mother's or the handyman's fault.
It is possible the pipe failed at the moment the water was turned back on, but not "because" it was turned back on. What I mean is, you have a burst pipe. It's not your mom's fault. There is no need to take special steps to protect your pipes while turning the supply on and off! It's wrong to say "she" burst a pipe "by" turning the water on or off.
Maybe the pipe was weak or poorly installed or corroded or ready to break for some other reason. She is lucky that it did so when she was at home, and not spontaneously when she was out for hours or days.
Maybe you have excessively high city water pressure and you need a pressure control valve. That would contribute to the failure. You could look into that. But it would have to be uniquely, freakishly high to burst a pipe with no other contributing factor.
If a pipe is about to fail, cycling water on and off is likely to take it over the edge. Everything breaks more often when it's turned off and on.
A bad Pressure Reducing Valve could make this more likely.
Water hammer can be quite destructive. If the system is turned off and back on there should be no effect. After doing repairs that allow air into the system you want to open the main valve a little and allow the system to refill, then turn it on fully.
Depending on the nature of the repair, checking the work when the valve isn't fully open may limit the damage caused by leaks.
