If your ball is in the water you can (under penalty of one stroke):
Note: If the ball is dropped in the dropping zone, the ball must not be re-dropped if it comes to rest within two club lengths of the spot where it first struck a part of the course even though it may come to rest nearer the hole or outside the boundaries of the dropping zone.
All fixed sprinkler heads are immovable obstructions and relief from interference by them may be obtained under Rule 24-2. In addition, if such obstruction is within two club-lengths of the putting green of the hole being played, and intervenes on the line of play between the ball and the hole, the player may obtain relief without penalty as follows: If the ball lies off the putting green but not in a hazard and is within two club-lengths of the intervening obstruction, it may be lifted, cleaned and dropped at the nearest point to where the ball lay which (a) is not nearer the hole (b) avoids such intervention and (c) is not in a hazard or on a putting green.
Match Play - Loss of Hole; Stroke Play - Two Strokes