Thanks @OldGuyot. The "Source Outdoor SNEP Convertube Water Bottle Adapter Into A Hydration System Kit" has received a lot of critical reviews on Amazon. I want to make a gravity water filter installation with the following scheme, from top to bottom: 1. Lightweight plastic (dirty) water bottle, with air-valve and extending hose-barb 2. Piece of food-grade silicone or PVC hose (1/4" inner diameter) 3. Grey Sawyer Inline Hydration Pack Adapter 4. Sawyer Squeeze Water Filter 5. Blue Sawyer Inline Hydration Pack Adapter 6. Piece of food-grade silicone or PVC hose (1/4" inner diameter) 7. Katadyn Active Carbon Bottle Adapter 8. Piece of food-grade silicone or PVC hose (1/4" inner diameter) 9. Lightweight plastic (clean) water bottle, with air-valve and extending hose-barb ... View more

Thoughts on Sawyer water bags: https://rei.com/conversations/backpacking/what-are-your-thoughts-on-sawyer-water-bags/m-p/20771#M1942 ... View more

Using CNOC water bags in combination with Sawyer Squeeze water filter: https://rei.com/conversations/backpacking/how-to-connect-sawyer-squeeze-to-cnoc-water-bags-and-carbon/td-p/20703 ... View more

@OldGuyot Thanks a lot for your comprehensive advice. I see that the Amazon website contains a lot of useful information from users, about the products we mentioned. ... View more

@nathanu Thanks, I consider buying two CNOC bags. Then I have one as a spare dirty water bag in my backpack, in case the other will tear. I consider buying the three liter CNOC water bags, since they are about the same price and weight as the two liter version. Does the blue coupler that you mentioned fit the CNOC water bag? I will also carry the Sawyer syringe, because backflushing the Sawyer Squeeze should be done with full force, according to the Sawyer manual. And the syringe is probably more sturdy than the CNOC. I found a number of videos about the CNOC water bags on the internet. ... View more

Thanks for your helpful mediation. I found many satisfied user reviews about the Sawyer Squeeze water filter on the internet. But many users have serious criticism of the Sawyer Squeeze's water bag supplied. Therefore it might be a consideration for REI to advise and sell the CNOC waterbags instead? I have no commercial interest in the CNOC company. ... View more