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.
Quick Answer. Pool water turns brown due to high iron levels. Water from certain sources, such as wells, contains dissolved iron that oxidizes readily and turns brown when in contact with air. Acidic pool water, on the other hand, deteriorates metal equipment in the pool, introducing excess iron into the water. Continue Reading.