Jeff Grigg from Manchester, MO on 10/5/2008 8:56:42 PM:
Yes, the bike shop is glad to let you use their restrooms (when open) and have as much water as you want. I drop by there every couple of weeks, in good riding weather, to stock up on snacks while riding the Katy Trail.
There's also cold water and restrooms at the "Weldon Spring Interpretive Center" (next to the concrete disposal cell "mountain").
I assume the same for the Busch conservation area building, at the end of the trail.