All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
If the water by which the impurity is washed spreads over something, and this water has changed with impurity, then whatever this water touches becomes impure. However, if this water has not changed with impurity, then it is ruled to be pure. In this case, whatever this water touches does not become impure.
If a person touches his clothes while washing the impurity, then his clothes do not become impure just because of this as long as he is not certain that it is stained with impurity.
Allah knows best.