What is your diet usually? I think I've read that a raw food diet can be gentler in breaking up kidney stones than fasting is. It may be worth in your case if fasting has been too difficult in the past to reverse your plan and maybe go 21 days raw, then 21 days juice and then the water fast. You will then need to recover from the Water Fast still but it might help you ease into the fast and avoid some of the symptoms that have caused you to end your previous fasts. No doubt the Water Fast will do the job, but it may be too quick a detox in your case.