Increased fluid intake for a urine-output of 2 liters/day is one of the most important and the least expensive form of conservative measure to reduce stone-recurrence. Its effect is through mechanical diuresis and decreased solute-supersaturation and formation-product ratio. Large epidemiological studies on >45,000 men (health professional follow-up study; HPFS) and 91,000 women (Nurses’ health study; NHS-I and NHS-II) found a 30-40% risk-reduction associated with doubling of fluid intake to 2.5 liters/day or more.[7,8]