I have some of the white nalgene bottles, not the clear ones.
They seem to be OK, just they have no loops so you need to have them in a bag.
(Somebody should make a pouch for a water bottle but I can't remember ever seeing one)
I sometimes use the light weight stainless steel thermoses for hiking.
Thermos/Thermocafe for example.
There is the same problem of needing a small backpack for them

I also use large size disposable pop bottles a lot.
You can not beat them for price, and when they wear out you still get your 10¢ deposit back.

Edit.
I was just thinking that none of my water carrying containers fit on a belt. They are all either in the pack or on shoulder straps.