My water bill went up significantly last month….could find no leak. Meter was not moving when no water in house was running. Plumber concurred....but ran dye test on toilets. One toilet in largely unused guest toilet showed constant very slow leak. We replaced the toilet. That seems to have fixed problem.....although it is still mysterious as to how such a slow leak could cause so much water to be wasted....??
But the plumber was prompt, efficient, courteous and thorough. He did his job ery well.