I've been trying to find a a few plastic containers (of different sizes) where the lid stays put and where the container will not leak (let in water), even after being knocked around. I tested (very unscientifically) a number of "Lock & Lock" and "Tupperware" containers that were in good condition that my wife and I had picked up at yard sales. I'm not concerned with liquids leaking out, only that they keep water out and the contents dry.
I was surprised to find that most all of the containers did not keep water out when I dunked them in a bucket of water. Also, I tried kicking them around a little (sometimes a lot) with them half full of water to see if the lids would stay on to the end that the container would still be liquid tight.
What I found indicated that no matter what the plastic containers looked like, the information from the manufacturer's website seems to be the best guide as to whether a particular container series is waterproof (liquid-tight). All the ones that leaked were containers that the manufacturer never claimed to be liquid tight. Containers that are just "air-tight", always leaked (with one exception). In other words, if you need a plastic container that will keep critical items dry no matter what, make sure the container's packaging label says, for instance, "liquid-tight" (or words to that effect).
The one exception that I found was a small Tupperware container from the "modular" series. The website does not state it is waterproof, yet I left it underwater for an hour and it did not leak. Also the lid did not come unsealed when I filled it halfway up with water and kicked it around.
As to Lock & Lock, the only ones that the literature indicates are liquid tight are the ones from their "classic" series. From Tupperware, it's the "Pak-N-Store" series.
Would OtterBox or Pelican work for you?
Sometimes you can improve the seal by adding duct tape or equivalent. It depends a bit upon the structure of the container.
I have two OtterBox's (the 2500 and the 3500) and use them a lot for certain purposes. These are both "clear" color ones and are really neat. Although they're well designed, waterproof and bombproof, they are a little bit heavy (at least for me when I'm on foot) considering the inside dimensions. I'm more looking for something that's light and can be thrown in my back pack.
I've tried using duck and air/moisture proofing tapes on a tin (even put in a desiccant) and it did the job fine. The only drawback, and this is just me, is that I'm always going into it (using, updating, adding things) and just didn't like dealing with the tape. However, I'm considering trying tape out again on a Trangia (aluminum) mess tin - the one with handles that could be substituted for a large plastic container - plus you can cook with it.
Thank you for the suggestion. The only drawback I've found with the ALOKSAK bags are that things can get crushed, such as my Katadyn water purifier tablets. That's the main reason I need a reliable solid waterproof container. However, the ALOKSAK bags are high on my list of alternatives.
Just found some info on the Nalgene 32 oz wide mouth. I'll look into this further. Thank you for your suggestion.
I've been looking at the aLOKSAK bag sizes and reviews, and they make a 12" X 12" that might be an excellent fit for an 8" X 8" X 2" solid plastic container --- or might even fit the larger of the two Trangia aluminum (mess) boxes (which are not waterproof, but otherwise make great medium sized survival kit containers).
In other words, you could add water-proofing or an additional level of water-proofing with an inconsequential gain in weight and bulk. + the bag itself has other uses.
LesSnyder - your suggestion definitely warrants a test. Thanks.