Yes, this is just a custom water material that resembles piss.
Included within the zip file is a test map vmf file and bsp file.
The test map also includes a trigger_add_tf_player_condition brush entity to apply the jarate effect on to players that enter the water volume. Note that for it to work properly water volumes cannot have a height of greater than 40hu otherwise the jarate effect could be washed off. (You can have it at 48, but players can crouch in the water to get rid of the effect.)
Installation guide: Extract the zip file and place the piss_water folder in your tf/custom folder.