[Fourputt]

Originally Posted by Fileygolfer

You ask one question here but then give an example that gives your question TWO answers.

1. You CAN'T deem a ball unplayable in a Water Hazard. (Rule 28)

2. You can deem a ball unplayable in a Bunker but must drop it in that Bunker or go back to the point you last played from.

Rule 33-2a states that the Committe MUST clearly define accurately the margins of water hazards and lateral water hazards.
In your example this has not been done so you could argue that it is infact Casual Water and you get Free Relief under Rule 25 at the nearest point of relief.

See Decision 26/3: If it is clearly a permanent water course, even if there is currently no water present, it is still a water hazard. If it is unmarked then you have to use your judgment as whether it's location would make it a water hazard or a lateral water hazard. No permanent body of water on the course is casual water, although an artificial pool or fountain could be an obstruction.

The Decision:

26/3 Unmarked Water Hazard

Q. An unmarked ditch on the left of a hole is in bounds, but the left-hand margin is out of bounds. Accordingly, it is impossible to drop behind the water hazard under Rule 26-1b. A player’s ball comes to rest in the ditch. Is the player restricted to playing the ball as it lies or proceeding under Rule 26-1a?

A. It is the responsibility of the Committee to define accurately the margins of water hazards and lateral water hazards — see Rule 33-2a. However, if the Committee has not done so, the ditch is, by definition, a lateral water hazard and the player should be permitted to proceed under Rule 26-1c(i).