Rinsing the bucket after washing impure clothes

My parents do not understand about najasat much. They clean the impure and the pure clothes together in the same bucket and later they do not wash the bucket and use it again for washing purposes. I have told them that the bucket becomes impure and has to be washed before used again but they are not listening to me and scolding me. When I talk about this now my exams are getting over and I have to go to my home and they wash the clothes the same way as they used to. So if I go and pray with the same clothes after knowing that they are impure will it be kufr and what should I do? Advice me.