Large capacity water softener for an RV. This is the larger size intended for full-time RVers. We were full-timing it for a few years, but health problems put a stop to that. We could go 6 months on a re-charge with this thing, and we always had good water in our camper no matter how bad the campground water was.
https://www.amazon.com/Go-OTG4-DBLSOFT-Portable-Grain-Water-Softener/dp/B00KVPNVJ6/ref=sr_1_1_sspa