How to remove feces stain from linens after it has been washed and dried?

One more thing, always wash the soiled sheets separately from other items. The smell can transfer in the wash onto other clothing.

I was just searching for this answer online the other night, because...yeah. Anyway, there are lots of answers in the mom and baby forums, and the most recommended things for post-dryer diaper poop are:

Oxyclean (most recommended - let it soak in cleaner and water first)

Hanging the (wet) item in the sun (you have to keep wetting the item as it dries)

Enzyme-based cleaner ("eats" biological matter without damaging non-biological material)

I use bleach every so often, but  not every time. I use cotton sheets for hubby. He is the only one who uses those sheets and doesn’t care if they are stained. I know they’re clean. Using bleach too much can weaken and shred the fabric, especially on towels. You can mix a tablespoon of baking soda and some hydrogen peroxide and let it sit on the stains for an hour or so. But with diet and medications our LO’s are one, complete removal is almost impossible.

Try hydrogen peroxide

At some point caregivers have to realize that "clean enough" is the goal to aim for, pristine laundry may not be possible. If you still want to try and you can't use chlorine bleach I have had good luck with liquid bleach substitutes and an old fashioned wash board.