This is a bunch of vmt files that enable reflections on the default tf2 water materials instead of cubemaps.
To install simply extract the rar to Steam\steamapps[username]
To see reflections you will have to have them set to reflect world or reflect all in the graphics options.
To uninstall simply delete or move the files, as the original files will still be in the team fortress 2 materials.gcf
Note: may not work on all servers/custom maps/new maps, and may cause water to disappear completely. May break with game updates, I don't know, I stopped playing this when they released the free to play stuff.