I too worked in the water purification business for 37 years before retiring. There are several acceptable methods for making water potable.
Ultra-filtration works (especially reverse osmosis) as does Ultra-Violet disinfection and chemical disinfection.
The most common problem in the mountain west would probably be parasites (chrypto, giardia, etc.). While UV will not necessarily kill 100% of all parasites, it will render them unable to reproduce... effectively preventing illness from ingestion.
Most potable water plants (with either underground sources OR surface water sources) use "all of the above" methods.
Bottom line for me? I've used both the PUR filtering system (now Katadyn) AND tetraglycine hydroperiodide tablets. Coleman is one retailer of such tablets. They also sell a follow up treatment tablet that is basically ascorbic acid which neutralizes (removes the residual treatment chemical) the taste and smell of the disinfectant.
I prefer the tablets as I have more confidence in the chemical reaction than a physical filter.
In the streams I have used as a water supply, parasites are my only concern. I also add tang or gatorade powdered drink mix as I like the added flavor anyway.
Whichever method you use should suffice.