Putting together a water filter that's going to get absolutely everything out of the water can be difficult, and should be reserved for long hikes, through hikes and more. If you're just going to be out for a while, or you want something that can work simply as an extra purifier, I think this might do the trick. It's also great just to have at home or in your case in case you're suddenly put into a survival situation.
I tried this a few weeks back and it works great. Makes rain water totally drinkable, which is mainly what I was trying to do since its a great source of water if you can enjoy the taste.
The weary might want to still boil it but overall its gonna work great. Just change the active carbon after about 4 months of use and you can keep going with this for years, really. It won't take out salt, minerals or viruses though so be aware of that. Choose a good source, filter it and your gonna be good to go.