Can you tell us more about the hum?
Is it only when running water at any faucets or full time?
Did you happen to turn the water pump on and it might be defined as a hum if it is running ?
There is a check valve which is a very small simple spring gizmo right where the hse attaches on lots of RV and that spring and plastic can get flipped or knocked a touch out of place and make a noise which I think of as "chatter" but others might call it a hum? It's first thing you see when looking in the hose connection and touching semi-gently with a finger or pencil to see it springs back into positon might be an easy one to check.
One common thing after water main breaks is there are often bits of minerals, rust, etc. knocked loose from the inside of pipes and it can go downstream to odd places and often wind up in the aerators of faucets, so it may help to check them as well if things tend to run a bit odd now. Just something to be aware of as it doesn't necessarily clear as things slowly work their way around in the system, depending on length and distance from the break.