OK, I know better but for some odd reason I attached then soldered copper too close to the cold water intake nipple of a brand new water heater. The plastic pipe within the metal male threads, on the water heater top, has deformed slightly. I see no external leak when the cold water fitting is attached but could there be an internal leak - a slow leak between the metal threads of the water intake nipple and the plastic pipe fitted inside?

Will a slow leak become evident or could this potential leak slowly destroy my water heater undetected? Can this type of damage be fixed before..

Your tank is glass lined. What you messed up is the "dip tube". This is a long tube to near the bottom of the tank.

If it wasn't there, the entering cold water would just exit the tank at the hot water side as the water in the tank was displaced.

It should be replaceable. Unfortunately, you'll have to uninstall and tip the water heater to install it.

Hello Workster,

If you don't have external leak and have no problem with hot water I guess you be OK.

If there is a problem with hot water for example you take shower and have hot water only for a few minutes then this is the indication of the dip tube is damaged like KeepItSimpleStupid says, see the link below and it will show how the Dip tube works, if no problem no need to change the Dip tube, if you need to change it is very easy to change it, Thanks,

John

How a water heater dip tube works and what it looks like. (http://www.masterplumber.net/electricwh/dip_tube.htm)