Water Heater Leaking

We have a Rheem water heater that is about 11 years old. Works perfect but it appears to be leaking from where the cold and hot water connect and also the pressure relief valve and possibly the annode. Odd thing is they all started leaking at the same time. They are corroded.

I was ready to replace the water heater and spoke to a plumber who said that the copper inlet/outlet should not be connected directly to the water heater. We have PEX which is connected to copper which connects directly to the water heater without any galvanized pipe. He said it should have been installed with a di-electric union which would have prevented the corrosion.

Is this true? If so, why would all of the fittings leak at the same time? Is this just a cooincidence?

Should I replace or repair the water heater?

Your leak goes beyond the connection...

The tank itself is leaking and the water is comming out available openings in the shell.

Trust me you need a new water heater!

And you don't want to buy it at Lowes....

Buy another Rheem or a Bradford White...11 years is good...you may not get that out of the new one...

Because of the potential excessive heat right at the WH, you can't connect pex or any plastic pipe directly to it...you need that copper stub. Many WH come with heat traps that also act like a dielectric union, but there are a lot of situations where that doesn't help much.

So with the use of PEX do I need a di-electric connector?

You don't need one between pex and the copper. If used or needed, you'd use one between the copper and the steel tank. It's possible that that connection is already a dielectric union and not painted steel.

Dissimilar metals in an electrolyte create a battery. In a battery, parts of one electrode change states, give up electrons, and end up being depleted. This only happens if the solution (the water) is conductive. Pure water isn't a conductor, but it's the impurities in it that can make it conductive. And, if there's no electrolyte, you get no (well there is some, but not anywhere near as much) battery (you can get a thermoelectric power source). How big a battery you have will depend on the two metals involved and how good the electrolyte is or how hot is is. Some people in some places find a dielectric union makes little difference. You'll get different answers depending on who you ask, and different manufacturers can have different installation instructions. Best to follow their instructions (they often give you them as part of the WH). Now, whether it will make a difference or not, can't say for certain.