How do you clean your Sawyer filter? I am using the plunger that comes with the inline filter we have on our hydration packs after our camping trips back flushing them with filtered water from our fridge. I read an article that said the small amount of water left in the filter after back flushing can produce bacteria and they recommened a very mild bleach solution instead of just water. Has anyone tried this method or any other suggestions? Will this damage the membrane? I tried contacting Sawyer and they never responded.