Brown or rust coloured spots on laundry can be caused by the following –
- Metal objects in the washing machine such as nails, paper clips. These often get stuck in the outer tub under the drum and start to rust
- Rust or iron coming through the water supply. If you suspect this hold a white piece of cloth under the tap and let water run through it for about 5 minutes. See if a brown stain appears
If the water is staining the white garment brown, run water through other taps before starting the washing machine to try and get most of the water out of the pipework. Also check the filters in the water valves to make sure they are clean. You may need to consult a plumber or water authority about this issue.
Try covering mild stains with salt, then squeeze lemon juice over the salt and leave overnight. Then rinse thoroughly and wash normally. There are rust remover products available for this problem for more serious stains.
Brown spots could also be caused by rust from drum bearings
A more rare cause could be actual rust from the drum bearings where the seal protecting them has allowed water into them. If this is the case you should also be finding the washer noisy on spin, check this article for further details rumbling, and very noisy on spin