Larger home water treatment systems such as reverse osmosis (R/O) or water softeners are usually set up with a timer device that limits their hours of operation. These systems are programmed to perform regeneration and cleaning functions when there is no other water use occurring in the house.
Ideally these devices should be programmed to perform regenerative functions between the hours of 2 and 5 a.m. when there is seldom any other indoor use. Research has shown that this is the period during which the least amount of indoor water use occurs, as shown in Figure 1 (Mayer et. al. 1999). Here it can be seen that less than 4% of all indoor water use occurs between 2 and 5 a.m. More than 88% of indoor residential water use occurs between 6 a.m. and 10 p.m.
Figure 1: Typical indoor hourly use pattern (Mayer, et. al. 1999).