This is why the Pharisees had water set aside in special jars. There was a ritualistic way of washing one's hands so as to be clean before God. It was a long established practice with the momentum of ancient things. But rituals are a doorway not a destination. The journey is not in the work of our hands but by the pilgrimage of our hearts.
Rituals can be empty, or at odds with reality.
It does no good to wash one's hands if the place needing cleansing is inside of us. Clean hands are not a substitute for a clean heart. This was what Jesus was talking about when he responded to the Pharisees who challenged the religious practices of Jesus' disciples. We could wash our hands in silver bowls before the altar and still not be clean. We could stand in the rain with our arms held up until we are soaked to the bone but the memories of things done and left undone will remain like a deep stain that will not wash away.