A systematic review of studies found that producing less than 900 mL of urine per day increases the risk of kidney stones, with a minimum safe urine output of 1.6 liters per day for those who've had stones before. The most effective beverages for prevention include low-calcium water, citrus juices, and blackcurrant juice, while cranberry and plum juices have less favorable effects. Drinking an additional 1.3 liters of fluid daily can help achieve protective urine levels and reduce kidney stone risk.