I'd like to switch all my water bottles to use either a dust cap or some kind of cover/protection against mud, road grime/grit, etc. I've searched the web for bottles with dust caps and I'm only finding lots of cheap chinese bottles of dubious material and undeclared components (BPA free? Not?).
I also looked at generic bottle covers or protective caps, similar to latex seat covers, so that I could use my existing bottles. All I found was the type of neoprene water bottle case that acts as a cooler, with an open top (the top is precisely the part I'd like to protect).
Then I thought of what else (apart from a plastic bag) I could use to adapt as a water bottle protective cover. Some ideas I considered were:
Nalgene makes at least two different kinds of bottles with covers for the drinking spout. I have two each of the two types. They have held up well for many years. I have dropped them at high speed, more than once, with no damage except a very small amount of road rash. I use them all the time. Mine don't leak.
Yes I have two of the small ones. Probably at least 10 years. When I bought mine they only sold white. The four Nalgene bottles I have are the only ones out of about maybe 30 bottles That don't leak. All the exposed spout typical bottles you see often eventually leak.
I also have two of these, I have the blue like the photo. http://store.nalgene.com/category-s/25.htm
I have had them maybe 5 years, can't remember. I like them but the ATB bottles are easier to hang onto, and a little easier to drink from when riding.
I bounced a full one off the road at 20 mph, It has some tiny hard to see scratches. It's OK.