Answered by Shaykh Faraz Rabbani
Question: What is the ruling of putting filthy clothes in the washing machine? If the clothing comes out clean and the substance of the filth (such as semen) has gone but a stain can still be seen, is the clothing considered clean? If not how many more times do i have to put it in the washing machine before it is excused?
Answer: Walaikum assalam wa rahmatullah,
1. If one washes semen from body or clothes and the substance itself is removed, then traces that are hard to remove (namely, anything not removed by a regular washing) are excused.
2. While it is permitted to put ritually filthy clothing in washing machines, it is religiously superior to wash away the filth first under the tap to avoid differences of opinion. As the scholars say, “There is nothing like safety.”
3. If one puts filthy clothes in the washing machine, it is best to wash the clothes in three cycles of water.
And Allah alone gives success.