I have a toliet that has a leak between the tank and the bowl. I have replaced the sponge washer and all the bolts. Still leaks out the back. Water appears to be coming back up under the sponge washer and runs down the back. There does not appear to be any defects in the porcelin. Am at a loss as to what to do next.
Just lift the lid on you cistern and make sure the inlet valve is not leaking, sometimes they leak when filling and spurt over the back of the cistern and run down the out side between the wall and tank