I've recently been convinced to give up my hydration bladder to drop a few ounces of weight. I have not yet, however, been convinced to give up my water filter. It's worth it to me to carry a few extra ounces in order to have (nearly) instant clean water. One of the nice aspects to using my bladder with my gravity filter was that I could just connect the bladder tube straight into the clean side of my filter with no mess. Filling up a soda bottle is easy enough, but it would be nice if I could set the bottle down without having to worry about it falling over or the hose falling out. Here's what I came up with:
At my local hardware store I found a 1/2" male threaded to 1/4" barbed fitting for $1 that fit the inside of a soda bottle with just a little bit of wiggle. I wrapped the threaded end with teflon tape, it took about 9 or 10 wraps to get it to just perfectly slide into the hole for a perfect seal. I then drilled a small hole in the top of the fitting as an air relief.
It works perfectly and weighs in at just under 7 grams. Here's some pics of the result: