I have a Watts Water Expansion Tank, I assume it is the 2 gallon size, that has developed a leak in the tank. It is attached to my hot water heater and when the cold water valve is turn on, a fine thin spray of water comes out of the top of the unit. It is not leaking where it is attached to copper pipes. It is about 6 years old, we build our house in 2001 and it was originally placed by the builder. I assume I will need to replace the tank. I have basically 2 questions. Any idea on how this leak could have come about? The unit is an all metal constructions. The second question, can this repair be done by someone with absolutely no plumbing experience or would it be safer to use a plumber?

If the tank's attached to the cold water line with a tee that it's a simple task to replace it. It threads in so shut the water off at the house shut off and bleed the pressure off. Now unscrew the tank counterclockwise. Don't forget to use Teflon Tape on the threads when you install the new tank. Good luck, Tom

Lets not forget the pipe dope as well as the teflon

If you use Teflon Tape you don't need pipe dope.

If you use Teflon Tape you don't need pipe dope.

Better safe than sorry though

Thank you guys for the quick reply. I'll give it a try but will call the professionals if I run into problems.