No, I did not notice this huge leak.

Can I unscrew the vertical rusted galvanized nipple from the tank, and then rebuild the outlet pipe to some downstream connection point where soldering is required?

You might, depending on how corroded that connection is, however there is a quicker easier way to do this without having to rebuild the copper.

Turn off the water to the house, cut the copper back past that old shut off valve, to clean copper coming out of the wall.

Then use a Sharkbite Push to Connect Water Heater hose. Makes fast and easy work to fix things like this, or replace water heaters.

No more copper hard connections that make service and installation a $500_+ labor job, all you need is a pipe wrench and a copper tube cutter.

They make one with a 90 degree cutoff ball valve which is quicker, safer than that old screw in shut off valve you have now.

Lowes, Home Desperate, either should have this in stock, if not Jeff Beezo's will drop one off in a day....


Link

Its actually as easy as the video shows.

Thank you for the guidance. How should I approach removing the corroded galvanized nipple to avoid over-torque on the top of the tank? Kroil?

2nd thumbs up for shark bite connections, but I gotta ask, How old is the water heater?

Heater is three years old if that.

It looks like that nipple needs to be replaced

I would cut the down tube where you can get a hacksaw or sawsall about half way up, then use a pipe wrench with smooth even pressure to loosen up the copper and nipple assembly as a whole unit, I think you'll get a better grip on the brass nut that was screwed onto the nipple.

Looks like they cut the down pipe and connected it back together three years ago when the heater was replaced?

You may need some heat to help if you can't turn it. A good sized pipe wrench where you have the ability to get some leverage will help.

You could spray some Kroll or any penetrating oil on it, but I'd probably put the wrench to it first and see if it will turn, that might be all surface schmutz and not down in the threads.

Shut off the water first.
I would cut the copper just below the coupling and behind the valve.
Replace the nipple in the water heater and use shark bites with a ball valve.
I would do this to both sides not just one.
If your so inclined I would drain the tank and get any sediment out.
Also get some thick copper ground wire and attach it it to the hot and cold pipes if it isnt there already.

At 3 yrs old, it'll probably unscrew from the tank.
But, I'd have a 3/4 internal pipe extractor just in case the pipe wants to collapse from all the corrosion.

Replace stop valve to nipple and all between. Id suspect the original fail was the squeezer coupling or the solder joint at the 90. And copper to steel is a no no.

Move the new stop valve farther back, and use a flex to the new nipple if code allows.

Ask about code and a dielectric union

Looks like the value has been leaking also. Likely just the packing which can be fixed by tightening the nut but I would replace it with a ball valve.

The simplest way if you don't want to solder is a new nipple to a male MTA shark bite, a short piece of copper, flex hose made for water heaters with shark bite connections to another short piece of pipe to a shark bite ball valve to the exiting water line.