need to extend the copper tubeing for the shut off valve to the toilet, in order to tile wall. Problem is,even with the main water valve turned off, the water flow is still at a constant drip, not allowing me to heat the copper for a good weld. Have tried bread to obsorb water,but flow is to great for a weld to take place. Of course the toilet shut off valve is the lowest(elevation) of the water line, tried opening other valves to drain off water, not successful, tried bread to soak up water while soldering, flow to great before tubeing can be soldered. Force air into water line to remove excess water? Any other ideas? Thanks C