Customer had leakage coming from the washing machine box. I ran my cable down the line to help remove buildup. I remove a little bit lint build up, customer has the back of the wall exposed. From what I can see the drain is PVC customer do not know if they have cast-iron. I tested the washing machine and ran three loads on a heavy load. I have no back ups if it happens again I’ll recommend having the supervisor team to come out to further investigate to see if cast-iron is underneath the slab.