Clogged Discharge Pipe in a Water Heater

Find out what to do when lime keeps building up inside the discharge pipe of your water heater and causing it to clog. Get tips on going to a plumbing supply store and asking for a plastic-lined nipple, which will…

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LESLIE: Ben in Illinois is on the line and is having some issues with a water heater. Tell us what’s going on.

BEN: Over a period of time, my hot-water stream would keep getting smaller and smaller and smaller. And then it got to the point where you turn the hot water on, it would just barely trickle. I disconnected the discharge pipe on the discharge side of the hot-water heater and found that the lime had built up so bad in the pipe, coming out of the top of the hot-water heater, that there was just a very tiny hole there.

TOM: Right.

BEN: At that point in time, I didn’t know what else to do. I just took a very large screwdriver and tapped that limestone out of there. Of course, that fell to the bottom of the hot-water heater. It’s been fine for about four-and-a-half years. It’s getting to the point where I’m going to have to do it again.

And I’ve talked to retired plumbers in that and they told me that what’s causing that is a reaction between the copper pipe and the metal that is on top of the hot-water heater. And I was told that there was like a nipple that you screw on top of the hot-water heater and then connect your copper pipe.

My question is: what type of metal is that that goes between the copper pipe and the metal coupling on top of the hot-water heater?

TOM: Yeah, Ben, all you want to do is head to a plumbing supply house and ask for plastic-lined nipples. That actually is going to create the sort of the bi-metal protection or insulation between those two pipes. And that will stop that corrosive effect that you’re seeing and of course, they’ll stop the pipe from clogging as a result of that.