The figure below shows the two main families of acetylcholine receptors: muscarinic and nicotinic. In structural terms, muscarinic receptors are G-coupled protein receptors, while nicotinic receptors are ligand-gated ion channels. They can be found on both sides of the synaptic cleft (presynaptic and postsynaptic).
After the pressure drops below 40 psi, the electrical switch turns on the pump and the pressure in the tank increases. Any failure in any component or loss of electricity can cause a well to suddenly stop producing water when a faucet is turned on.
Water, when it freezes, expands and this causes the pipe to burst because it does not have the space to contain the expansion. So, when winter is over and the ice starts to thaw, the water leaks out of the areas where the pipe burst which could be anywhere in the water supply system.