To relieve the pressure in the tank, just drain it.

When you mentioned turning off the red knob for water, I assume that you are referring to a red knob for a water line going into the tank. If not, then it's just a matter of finding the water line that feeds the tank.

This will stop most of the remaining water from leaking from the tank, but some may remain.

It's good to hear that someone is coming out tomorrow.

Regards,

My floor is getting destroyed over all this water!

that you're not stepping in water while touching anything electrical.

Hopefully, your insurance will cover most of this.

If that's the water to put the previous poster said

Some fire departments will send out a truck with a vacuum as a courtesy. If they'll do that without a charge, this could help.

If the fire department doesn't do that in your area, you might consider getting a wet-dry vacuum cleaner from a hardware store or big-box store.

If the floor is wet and you want to handle this yourself, please be careful to avoid any kind of accident with the electricity. Wearing rubber boots can help if you have any. If you are unsure this, give it a pass.

I realize this is more than I can handle.

The emergency plumber has been called. He's on his way.

Thank you for all of your advice.

Bummer, this is gonna cost me out the ass.

First of all lift the pressure release safety valve. Will be near the top of the cylinder with a little tag on it that says you should have replaced it 5-10 years ago. when the sound subsides to nothing or a tiny gurgle let the valve close.

With hose, bucket and towels to hand, disconnect the lowermost water pipe, and attach the hose. Standard garden screw fittings should be the right size. Or you can shove an unfitted hose into the brass nipple and wrap it in tape, (anything will do since there's no pressure to worry about).

Vacuum should keep the flow down to a trickle whilst you do this.

If you're lucky the cylinder might even have a separate drain fitting you can use to avoid all of the above.

Once you have the hose connected, reopen the pressure release valve to release the vacuum, and depending on the temperature of the water, water your garden or the driveway.

Google "draining a hot water cylinder"

Once they spring a leak, they're dead. Even when it's the overflow that starts to drip, it means that mineral deposits inside it have frozen something and it might be time to replace it if it's overfilling.

I'm waiting for mine to go, it's 17 years old. I've never asked it to do all that much, but 17 years is the upper limit for them around here.

I'm strongly thinking of replacing mine with a tankless. The installation cost is very high, but they're more economical and last 3-4 times as long as a tank heater and I'll be long dead and buried by the time it conks out.