We’ve been doing fine with just one filter setup for 20+ years – until we took our first trip to Quartzsite, AZ. Within less than a week our toilet got clogged with calcium and would barely flush. Twice I had to completely take the toilet out and ‘pick and blow’ all the fittings out so enough water would flow and flush as advertised. So now I’m on the hunt for SOMETHING to remedy this problem (short of reverse osmosis which wastes too much water). Maybe two (or more?) filters? Gasp! We love going to the Quartzsite area so not going is not an option. I hear this water problem is an Arizona problem, so I guess it’s not just the Quartzsite area.