Personally, I find the best way to water inflate is with an enema kit. Not only can you hold more that way, but you also dont risk getting water intoxication by drinking enough water (assuming for the enema kit you add salt to make it isotonic), plus, you dont have to worry about holding your pee, and if you go the extra mile and get some extra equipment, dont have to clench your anus to hold in all that liquid. I find water inflation gives a heavier, stretchier, and non-painful (aside from cramps) expansion, but thats just me. And I've tried air for years. Also good and less messy to empty, but I find much more crampy and painful, and movement is quite restricted.
Personally, I find the best way to water inflate is with an enema kit. Not only can you hold more that way, but you also dont risk getting water intoxication by drinking enough water (assuming for the enema kit you add salt to make it isotonic), plus, you dont have to worry about holding your pee, and if you go the extra mile and get some extra equipment, dont have to clench your anus to hold in all that liquid. I find water inflation gives a heavier, stretchier, and non-painful (aside from cramps) expansion, but thats just me. And I've tried air for years. Also good and less messy to empty, but I find much more crampy and painful, and movement is quite restricted.
(Not on here too often, replies might be slow.)