@Bob- "Dean, if the Sawyer filters are so good, then tell us what the Army uses."
On maneuvers? Gigantic diesel-powered reverse-osmosis water purifiers. Didn't you see that Pauly Shore movie?

I don't see THAT fitting into your pack any time soon, Bob. :o)
But for practical reasons in CONUS usually we just bring along tanks of potable water from the local water main.
But in Iraq and Afghanistan?
Believe it or not, often it's bottled water.
The deployed military consumes it in vast quantities because it is safe and easy. You can leave skids of it laying around anyplace convenient, where soldiers can grab a bottle, without having to worry about recovering a tank or blivet. It is also easily transportable to remote locations by loading skids of it into Chinooks, etc., without having to bring a tank or blivet back to refill. I shudder to think what future archaeologists are going to think about the PET stratum in the Middle East and Central Asia in a few million years.
If you're asking for instance what the "special people" use in the back country, I honestly don't know. I do know that the Army still stocks vast amounts of chemical water purifiers and that they still figure prominently in the manuals. Several manufacturers list the US military, among others, as a customer on their websites. Chlor-floc, is pretty standard, IIRC.

But, remember, one of the primary characteristics that the military looks for in any technology is that it is "soldier-proof." Chemicals can be issued as expendables- no device to account for or maintain. And the issue of freezing filters would be a significant one for the military. (And there is also a great deal of institutional inertia.)
I also know that MSR is making or has recently introduced a military version of the MIOX. Despite my belief that it is an AWFUL ultralight water purification option, it is probably a rather handy device for the military. I don't know if anyone has adopted it, but the special people can pretty much buy anything they like.

And I know that Katadyn makes the desalinators used on life rafts and aircraft ejection seats. I'm not sure if they make any other units used by the military but I wouldn't be surprised.