Well, the pipes most likely are not the problem. But I do know the drains can be. If the wax seal under the tolent isn't working properly that can create a leak every time it is flushed, cracks the the drain pipe on the washing machine can also cause a on/off leak. Lastly if you have a drain in the floor or the main drain from your house is partly blocked (roots, partly broken pipe) this can cause a slowing of the water draining from your home. As such a basement level tolent could back flow is the valume of the water exceeds the drain rate.
(no subject)