Potatoes can be peeled and cut up to a day before cooking, but must be placed in a dish of water in the fridge to keep them from drying out or browning. Placing them in water stops the potatoes from oxidizing and helps ensure that they will be moist and tender the next day.
Potatoes are able to keep well in a bowl of water for around 24 hours. However, it is important to wash potatoes both before and after peeling so that they do not soak in dirty water. Potatoes are grown underground, so they will keep better without their skin in a cool, moist environment.