looking for any input from experienced powerlifters (or fighters to I geuss) How much weight can you cut water wise and not affect performance
thats debatable. If you plan for water loss, 10lbs is not too bad. Although it is a blurry line where performance starts getting affected. This is just like anything else, it can be debated, and it is different between any two people.
it also depends on how much time you have between weigh-in and competition.
Start about a week out. Up your water intake to 2 gallons and keep it at that for 3 days. The next day drop it down to 1 gallon. The next day drop it to a half gallon. From there on out play it by ear, but don't go over a half gallon. The last day you should be taking in very little water if any, if you still have weight to lose.
You can lose around 10 lbs by doing this. It never effects me because I can get a bloat of 15 lbs in a day.