I use an older version of a Brita fill-and-go bottle with a filter. I like having a filtered bottle when I'm traveling to improve the taste of water out of drinking fountains and sinks. The older model also has a wide mouth that allows easy cleaning of the interior, plus I can put ice in the bottle along with water.

It's not insulated, so I have to put it in an insulated carrier if I want it to stay cold for a while.

The currently available Brita sport bottles come in four capacities and two materials - an insulated stainless and a single-layer transparent plastic. I don't like them as much as my old soft-sided Brita, but they use the same type of filter and get the same results.