A water purification system is disclosed which, includes a reverse osmosis (RO) system or component that is connectable to a city or other outside water feed that is capable of responding to and compensating for low or no feed water pressure coming into the RO system to ensure the outgoing supply of purified water is provided consistently and at a minimum water pressure. This can be accomplished without the need for communication with another device or system-wide facility, such as a hospital, or a pharmaceutical or semiconductor manufacturing system, requiring a constant water supply.