Mishaal,
If there is a standard, many years of looking for it have failed to turn one up. There's bits and pieces in several places. Most states in the US have regulations about the quality of water that must be met before discharging test water onto the surface or into agriculture or rivers. Pretty generic stuff for the most part.
I like to use water that is pretty nasty (e.g., produced water with moderately high TDS, pH above 7.0, and minimal hydrocarbons) already because it can't get much nastier. I can usually return this water to where I got it.
If I start with city water, then it gets rusty, has disolved gases that mess up the test etc. Disposing of the red-looking water is often a big problem.
Water from lakes, rivers, ponds, bar ditches and other untreated sources always have bacteria which can yield corrosion problems, H2S generation and other really bad problems - and you can never put the water back into the river because it looks bad from the iron oxide you've washed off the pipe.
David