I'm new at this so please bear with me. I want to purchase a reverse
osmosis water filter for my house. I have my own well and in searching for
a filter system, I noticed that some are made for city water, some for well
water and some for different ranges of PSI. I need to know how to measure
the PSI. Is it the reading on the tank gauge when it turns on and shuts
off, or do I need to buy a gauge that I can hookup to an outside faucet?