I have heard about minerals like calcium that build up in the hot water heater of a RV over time. We deal with the same issue in our home with hard water, so we know the issues that water with lots of minerals can cause. I was a little skeptical about how effective a portable water softener would be, but after our first use during our stay at Disney’s Fort Wilderness Campground, I am a believer. Taking a shower was amazing with the soft water this unit gave us. To recharge it takes only two regular sized boxes of table salt. It really is an amazing product.