Potato Salad accident
What would cause a potato salad to become watery about two or three days after it's made? This has never happened before and we can't figure out what happened (I'm not the one that made it).
It looks and taste like someone dumped about 1/2 - 1 cup of water in it. The flavoring is also very weak/bland as if there's not any flavoring in it at all. I'm not permitted to give the exact recipe (family secret) but I can tell you that the ingredients are peeled potatoes (of course), eggs (whites or wholes), onions, celery, confectioners' sugar, vinegar, salt, pepper, mustard, and mayonnaise.
I was thinking that someone measured out something wrong but I can't see anything that would make it watery. So I thought that maybe it came from the potatoes or eggs somehow. Another possibility is that someone accidently or purposefully dumped water in it. Other than that, we're stumped. Any ideas?