Here's my input on this subject --
Based on my experiences, I know of a couple ways to piss "water", or clear piss. The first that comes to mind would be to dilute your system, intentionally or not.
Hyper saturating your body with fluids will dilute metabolites in the urine. Diluted urine contains low creatine levels. so if you have a drug test coming up for anything, get some creatine in you. Diluting your system produces a clear urine, so once again, drug tests may reject it simply for its color alone. And honestly, I don't see why you WOULD be posting this unless you had some sort of drug test coming up, clear piss is a normal thing for everyone. This is also known as flushing a system.
Another way to piss water is to deprive your body of Vitamin B, and have low levels of Vitamin C. Many people will argue that Vitamin C is better for coloring urine, however, if you deprive yourself of vitamin B, regardless of how much vitamin C you take, your urine will not contain the color yellow, outside of a possible faint beige color due to extreme amounts of vitamin C.
If you're looking for yellow piss again, take plenty of Vitamin B, specificly B-2 or B-12, which is found in a B-complex vitamin in abundance. Don't overdo it though. Drinking less fluids wouldn't hurt, but if you're thirsty -- chug it narc. Don't deprive yourself of a basic bodily need. Drink plenty, remember, anytime you're thirsty, your body is dehydrated. Just make sure you're ingesting enough Vitamin B, and you shouldn't have a problem.
if you're looking for immediate results, crush up a vitamin B into a fine powder, and consume that. Within an hour or two, your urine should be colored once again.
Perhaps you drank bleach?
When you start SHITTING white, that's when you worry about this