I use sea salt and filtered water for pink eye/conjunctivitis all the time. I have 4 kids and for some reason they are susceptible to pink eye. (I've gotten it a few times from treating them... Very contagious) I have little rubber 1/4 c dishes (from kitchen) and use them to mix 1/8 tsp sea salt with 1/4 c water. I make the child put eye up to cup and tip head back (kind of suctions to their eye), they open eye as much as they can, then dump out and rinse container. Do same with other eye. Don't cross contaminate or will spread to other eye. Only takes about 3-4 days. I do it 3 or more times a day. Dry with a clean, new cloth each time. Do not rub eyes with same hand... Will spread. Might sting slightly, but usually their eyes feel better almost right away.
As a child I had a horrible case of conjunctivitis. For over a month, I suffered from home with absolutely no change no matter how much eye drops or medication the doctor's prescribed me. My family finally took our yearly trip to the beach and after a day, my eye infection was completely gone. When we returned and returned to the doctor for a checkup, my pediatrician chuckled and said, oh "You went to the beach, the ocen clears that right up!" My mother could NOT believe it. We surely would have hightailed it to the beach a week into the conjunctivitis had we known! As a result of my month long infection, I had permanent vision damage and had to have membraned PEELED off my eyelids. I am just thankful the beach trip and swimming in the ocean happened when it did, otherwise, I might have had even greater eye damage. I'm lucky I only have to wear glasses/contacts for the rest of my life.