Originally Posted by CraigFL
I agree with glennjanie but you may already have a water hammer absorber pipe and it just got "waterlogged". Over time, the air cushion in the pipe can become filled with water and then there is no cushioning effect. If this happens, all you need to do is drain the water from a low point in the system and then turn on the water again which will trap new air in the pipe.
So, I'm going to try this. I hear the knock and then I hear the a running noise with the toilet.
Do you mean shut off the water main and then let the water run till it's done -- from a low point would be downstairs where no sink is hooked up right now. Maybe I could use the washer instead. Is this what you mean to do???