With all this heavy rain, you should know your options if you hit your ball into a bunker that has casual water in it.
First, read the definition of Casual Water.
"If the ball is in a bunker, the player must lift the ball and drop it without penalty within one club length of and not nearer the hole than this point, except that the ball must be dropped in the bunker."
What happens if my dropped ball rolls back into the water? Rule 20 tells us that you must redrop the ball if it rolls and comes to rest in a position where the interference by the condition from which you just took relief (in this case, casual water).
There is another option - but this one has a price!!
Rule 25 goes on to say that if your ball is in casual water in the bunker "under penalty of one stroke, you can drop a ball outside the bunker keeping the point where the ball lay in the bunker directly between the hole and the spot on which the ball is dropped with no limit to how far behind the bunker the ball may be dropped." (See line x-y for ball A1 or line x-z for ball A2) in the photo.
Sometimes, after a really heavy downpour, the bunker may be completely filled with water, and there is no place to get relief in the bunker.
Rule 25 b(ii) ... "if complete relief is impossible, drop the ball as near as possible to the spot to the spot where the ball lay, but not nearer the hole on a part of the course in the bunker that affords maximum available relief from the condition." Decisions from the R&A refer to water in the bunker that is "shallower" than where your ball originally lay!
Can the committee just declare that the flooded bunkers are out of play?
No it can not as per Rule 33 (The Committee) does not allow the committee to make a local rule providing generally that flooded bunkers are ground under repair through the green.
However, in extreme circumstances where specific bunker/s are completely flooded prior to a competition commencing and there is no reasonable chance of the bunker drying up during the competition, the committee may introduce a local rule for the day to provide that a specific bunker or bunkers to be ground under repair and classified as through the green. Only then may relief be taken outside the bunker without penalty in accordance with Rule 25-1b(i).