Why would my white sweater have light brownish-red stains after I take it out of the washing machine, but not before? Fortunately, I was able to save it by washing it with Shout, but I’d like to stop it happening again.
Do you have any rust or iron in your water pipes? That can do it.
I think pkbites has it. I’ll bet your water was turned off and back on between the last time you washed, and the time you stained your sweater.