A properly sized water softener uses an efficient amount of water for each regeneration, based on household water pressure (PSI). Keep in mind that a typical five-minute shower uses between 25 and 50 gallons of water according to the EPA. Oceanus systems have the following regeneration water usage: Occasionally a customer will undersize a system to take advantage of lower regeneration water usage, without taking into account the time between regenerations. This is actually less efficient. For example, if a 70 grain system is installed in the place of a 90 grain system, each regeneration uses 15 gallons less water. However, regeneration occurs nearly twice as often. For this example, in a four-week period the 70 grain system regenerated nine times, using a total of 405 gallons of water. The 90 grain system regenerated four times for a total of 240 gallons. Clearly a properly sized unit is more efficient (almost 2:1 in this example) in the long run based on gallons of water used. The inverse is not a good idea either. Over sizing a system to take advantage of the most efficient water usage allows too much time to pass between regeneration cycles. This allows naturally occurring bacteria to grow in the system and creates a sanitization problem inside the water softener.