Pat
I really don't want to beat a dead horse with this issue, but as I explained previously your solution is very simple. We have lived in the Phoenix area for 7 years now. We installed a whole house water filter the day we moved in. We drink water straight from the taps and it tastes as good as anything you pay for in the stores. I know you prefer to spend the money on bottled water, but that is your choice. After 7 years we have no crud on our shower heads and no buildup in the water lines. I use the water right from the faucet to brew coffee and only the change in the beans that I use is noticeable.
You can get the same equivalent setup from the Water Packer or the Water Store, both are vendors at RV conventions and both have displays at QZ, also both have web sites. Both do an excellent of explaining and selling. I got my setup from the Water Store before I met Lowell of Water Packer but I would trust both. I have a 2 "can" filter setup; the first has a sediment filter ($2.50), the second the KDF filter ($30, good for 2 years, same material as in my house filter). My coach water lines are clean, my sprayers/shower heads are clean and I save a lot of money by not having to buy bottled water.