First let’s talk about why cut potatoes need to be immersed in water to begin with. The reason is to prevent the potatoes exposure to air, which causes dehydration, oxidation, and discoloration. Immersing cut potatoes will also help rinse off excess starch. Also, it’s best to remember that just plain water isn’t enough – add 1 tablespoon of concentrated lemon juice or vinegar to each gallon of clean water to prevent oxidation. Use clean containers for this purpose, such as food-grade bus tubs.

As to the question, how long immersion is necessary? Only as long as you need to hold the potatoes until needed for the fry stage(s). This could be as little as a few minutes – to overnight storage in your walk-in cooler.

You can find more information on this at the following link: https://idahopotato.com/dr-potato/ten-steps-to-better-homemade-idaho-potato-french-fries.