Ask Dr. Potato
Q: How Do You Keep Your Potato Salad From Becoming Watery Or Soggy?
A: Chances are that an overly moist potato salad may originate from using potatoes with a lower solids content such as yellow (Yukon) or red types. While both have excellent potato salad qualities, they are sometimes prone to having a higher moisture content. Try using a russet variety next time to compare and contrast, as these have consistently a higher solids/lower moisture content.