What is regeneration, and why does it happen at night?

Regeneration is the cleaning cycle that restores the softener’s resin. The system flushes the resin with brine, sends the collected calcium and magnesium to the drain, rinses the tank, and prepares it to soften water again.

Regeneration is usually scheduled overnight because most households use little water then. Modern demand-initiated systems track water use and regenerate when their available softening capacity is nearly exhausted rather than running on an arbitrary daily schedule.