Multiple times a day my water pressure (from a well) drops to zero for approx. 30-60 seconds, then comes back on. It happens when we run too many things at once, or even filling a bathtub.

There could be several reasons for this. Check these in this order.
1. Check valve may be bad causing water to bleed bad back to well, replace it. Inexpensive fix
2. The switch may be bad. Relatively inexpensive repair.
3. The well pump may be going bad. Impeller.
4. The well itself may be going out. When the pump kicks on it may be taking some time to build pressure due
To low volume of water in well.
RJ