Deck Stain

I have two 4' x 40' Tommy Dock cedar docks at my cottage. When they were about two years old we cleaned both up and stained them with Cabot semi transparent stain. The one dock turned out great but the other we had issues with the stain peeling so I need to restain them this spring. I've read a lot about sanding, stripping and/or pressure washing but I'm not sure which method would be the best for my docks. We have a shallow well so I'd be a little worried about using any harmful chemicals as it could get in our drinking water. Could I just scrub them with bleach, then pressure wash them? Or what would you recommend? Could I then again them while they're on the lake or would them being over water make the stain not adhere right? I've never had a deck or anything so this is relatively new to me. Any help would be greatly appreciated!

Hello everyone, I'm finally going to start working on my deck. My deck currently uses the floor joists from the 1st floor of the house as the base for the flooring. Over the past few years I have painted it with water proofing, but that hasn't helped. Towards the edge of the deck the joists are badly rotted. I am hoping to take the deck apart and sister some 2x12s to the joists coming out of the house. I'd like to stop this type of rotting from happening again but don't know what to use. Standard paint on waterproofing isn't helping. I'm going to buy pressure treated wood this time and was thinking of getting some type of joist cap to line all of the wood with. I also looked into draping a waterproof membrane across each joist as well. The Trex escape system looks nice, but I'm sure it's very expensive. Any ideas?