September 20, 2022 2 min read
The day override setting on a water softener is a numerical value that sets the maximum number of days that a system can go before it regenerates.
Most modern softeners are metered water softener systems. That is, they measure the amount of water that is processed by the softener and initiate a regeneration based on this processed volume of water. This is what makes modern water softener so much more efficient than their "calendar clock" predecessors.
But sometimes water softeners can go so long between regenerations that it can be harmful to the media inside the softener that does the softening (this media is usually called resin). This may happen when the occupants of a home are using much less water than usual because they're on vacation or for any other reason. It's especially dangerous to a water softener when it goes a very long time between regenerations and the water contains foulants such as iron or manganese which can harm the resin if they aren't rinsed from it on a regular interval. It's usually private well water that contains these elements but some municipal sources will have them also.
Typically when the water source is well water, the day override (DO) value is programmed to 7 days. This means that if the softener doesn't regenerate on its own due to the volume of water used, the system will initiate a regeneration on the 7th day. For municipal sources without iron or manganese, it's common to set the day override value to 14 or even 21 days.
With this being said, there are some specialized water softener resin products that are specifically designed for high-fouling environments and these can often go longer without being regenerated with no harm to the resin.