Question: How does one wash a piece of clothing with najis on it?
Answer: Either by putting it under flowing water until one thinks the najaasah is removed completely, or by washing it in a bucket of water 3 different times with a change of water and wringing it until the water stops dripping all 3 times. After that one washes the bucket once.
This is if the najis has no trace. If it has smell, color, odor or body, then one washes it until the trace is gone either by flowing water or by several buckets. However, if there is one trace left that can't be removed without using boiled water or soap, then this trace is excused.
... and Allah knows best.