iPad water damage

There really isn't that much you can do yourself.

What do you need out of it? Apple wouldn't consider it eligible for anything other than "other damage" repair unless you have current AppleCare+. Apple won't repair an iPad with water damage. Perhaps a third party repair shop could try. Any kind of electronics with water inside needs to be dried out.

Water and electronics do not make happy bedfellows. Your iPad is not designed to be water resistant. While it may survive being splashed with water if immediately dried, it will almost certainly suffer irreparable damage if submerged.

Some users report that attempting to dry-out an iPad using a suitable desiccant (e.g., silica-gel granules - do not use rice) may be successful - but first, so as to minimise the risk of further damage, it is essential that the iPad is fully shut-down and not used. Seal the iPad in a ziplock bag along with the desiccant and exclude as much air as possible - then place in a warm dry place for several days. You should note that even if dried-out, there may be irreparable damage to the microelectronics.

Otherwise, you would be best advised to take your iPad along to the Genius Bar at your local Apple Store or Apple Authorised Service Provider (AASP) - where the technicians will be able to assess your iPad - and you’ll be in the best possible place to explore your available options for repair or replacement:

Genius Bar Reservation and Apple Support Options - Apple

If you have benefit of an active AppleCare plan, your iPad will be covered for accidental damage - including water-related incidents.

I’d point out that Apple really has no true repair options for an iPad other than maybe a battery. And with that much water inside it’s going to be obvious. Apple wouldn’t even try to refurbish that.