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.
Private wells can become contaminated with bacteria or chemicals such as nitrates. Bacteria - When a water test shows the presence of bacteria, it is considered unsafe to drink until the problem is fixed and the well is disinfected. The absence of bacteria in any one test does not ensure safety at other times.