How to be sure that my lifeproof iphone case doesn't leak?

I want to make sure my lifeproof iphone case doesn't leak but i don't want to constantly be taking the case off and on because everytime you do that it weakens the seal

Fill it up with something that reacts with water by changing color (or some other combination I'm sure you can find something pretty easy, google it.close up the case then swish it around in the water and bang it up against stuff in the water. Then dry the outside of the case off and open it up too see if there were any leaks

I have no idea!