Apple documents safe cleaning methods within this support page:
How to clean your Apple products - Apple Support
Water (or other liquids) and electronics generally do not make happy bedfellows. Your iPad is not designed to be water resistant. While it will survive being splashed with water if immediately dried, it will almost certainly suffer damage if it is allowed to get wet, or is submerged for any length of time.
If the worst should happen, speed is essential. If the iPad gets wet, it should be immediately dried with an absorbent towel - then set aside in a warm, dry location to throughly dry. If the iPad should be turned-off - and no attempt made to turn-on, use, or charge the iPad until you are absolutely certain that the iPad has fully dried out. Pay particular attention to the charging port.
If you need to seek assurance that the iPad is okay, a visit to the Genius Bar at your local Apple Store or Apple Authorised Service Provider (AASP) will provide opportunity for the technicians to test and assess your iPad damage:
Genius Bar Reservation and Apple Support Options - Apple