DEAR DR. ROACH: While reading one of your recent columns, I learned that all water, except distilled, contains electrolytes. I wondered if there are differences in the amount of each electrolyte in drinking water in different places in Canada, and if so, whether that might explain why I experience cramping and diarrhea when I am visiting another place? Through experience, I have been able to avoid the problem by drinking only bottled mineral or distilled water when I am away from my home. In cases where I have been on lengthier holidays, after I lived through the initial distress, eventually, my gastric system calmed down and seemed to accommodate the new source of water. I felt that my malady might be some sort of domestic version of Montezuma’s Revenge, but the analogy is inapt because the water I have consumed away from my home was not contaminated. -- M.T.