Hello tillymint666 and Welcome to Mrs. Clean's Forum:
I understand your frustration with trying to wash and getting yellow spots on white sheets. There could be a number of reasons for this. As you mentioned, you live in the mountains.
1. Your water could contain a higher amount of iron than city water. You could tell this by a slightly sulferish smell to your water. Another indication would be that your toilet bowl is yellowed.This would lead me to believe that it could be minerals (as you said) or specifically iron. If you have high iron content in the water (possibly a sulferish smell).
2. I don't know how old your plumbing is or what type, but cast iron pipes do get rusty and transfer that rust to all the faucets. You can tell if your pipes are rusty by removing the aerator on the kitchen faucet and looking to see if you have small flakes of rust particles in it.
3. Your washer tub (or drum) could have a small spot of rust that could be contaminating your laundry. It would most likely show up on whites. If it is at the top, it may only show up when you do a full load, hence not all the time.
If any of the above reasons are the cause, the only remedy is to fix the issue. The rust, to my knowledge, will only come out of fabric with a rust remover..which is highly toxic.
If it is other mineral stains or some other culprit, I do have a few suggestions. First, start with an “oxy” added laundry detergent or you could just add hydrogen peroxide to your regular liquid detergent (which is more economical). If you are not successful there are a number of other things to try such as sunlight, vinegar and water, cream of tartar & aspirin. See the exact instructions to remove perspiration stains at:
House Cleaning Central.
Good luck and please let us know how it turns out.
Mrs. Clean
Mrs.