My first experience with Xtol was ugly - I used tap water, and at that time I lived in a city where a lot of iron particles were in the tap water. There were little spots all over the negatives. Next time I bought 'demineralized' water in a 5 liter plastic canister, put the whole canister into a bucket filled with warm water until the content of the canister had the right temperature. Then I poured in the contents of the A and B bags, screwed the cap on the canister and started shaking it for a while. Then I allowed it to stand until the next morning, shaked it again, then filled it into glass bottles and added some butane gas (heavier than air, prevents oxidization). Now my Xtol now works fine for 6-8 months. I use it as a one-shot developer 1:1 or 1:2. There is a thread about using bag-in-box containers in this forum. In the meanwhile I heard from several people that they store their Xtol in these dirt-cheap containers, it lasts for a very long time.