If your washing machine’s drain is overflowing by the wall where the discharge hose goes in, it is likely due to a clog in the drain pipe. The clog could be caused by lint, dirt, and other debris that gets deposited into the pipe as the machine washes your clothes. To fix this issue, you will need to remove the clog from the pipe. This can be done by using a plumbing snake or other tool to reach into the pipe and clear the blockage. Alternatively, you may need to replace the pipe if it is too damaged to be cleared.