 Jennifer & the jealous travellers
Easy water filter and purification bottle. I was away for 6 months and I had such an easy time with getting clean safe drinking water with this bottle (aqua pure traveller).
The screw on cap does all the work. I had two filter caps, one for spare, and I used the first cap for all my drinking/cleaning teeth/washing hands water every day for 4 months before it started to run out. Then I switched to the new cap and it was still fine 2 months later when I got home.
But it is so easy and I didn't have any stomach upsets or diseases at all, despite filling my bottle from taps in the street in Nepal, taps in India, etc. I didn't try ground streams cos I never had to, but I reckon fresh running streams would be ok, because the street taps I used in the Himalayas were from mountain streams. Maybe you wouldn't try it with Ganges water!
For a few days the water tastes slightly chemically, then it tastes fresh after that. It says on the bottle to shake and wait 15 minutes before drinking, but I got lazy and drank the water straight away, and I was fine. You squeeze the bottle to get the water out through the filter, it doesn't pour out on its own. You open and shut the mouthpiece with your teeth so no dirty hands involved, and when it's shut it doesn't leak in your bag.
It costs 40 quid for each filter cap but every traveller I met was so jealous, cos they were fighting with iodine or whatever tablets it is you use for water purification, or always on the look out for where they could next buy trustworthy bottled water to lug around (leaving a mountain of rubbish behind them), while for me it just wasn't an issue, ever.
I got mine from Amazon I think, the main company sells and posts them too.
You can't even go wrong at the end when the filter cap is running out, because it just clogs up more and more, so you get to a point where you can only squeeze out a few drops of drinking water. Then you know that cap's dead. :) | 
