I recently installed my new hot water heater. I know nothing about plumbing and my installation procedure was informed only by sketchy home depot employees and youtube. One of the issues I'm having is that the nipple to tank connection on the cold supply ( water in ) leaks; it's a pretty slow leak so I just kind of watch it for now. I used Blue Monster thread tape. However, I was unaware of the technique of wrapping the tape to match the rotation of the pipe so that it doesn't mess up the tape when you start turning the pipe into the tank.

Note, the water is specifically coming out of the nipple to tank connection. The water accumulates down in the little well in which the tank's female threads reside. The only other potential source would be the connector hose to nipple connection and it's subject to an easy visual inspection that shows it's not leaking. I'm using a flexible, stainless connection hoses, not soldered copper to connect my heater to supply lines.

On the internet, I mostly see recommendations to "muscle up" and tighten it even tighter. Well, muscling up with a 14" pipe wrench seems like an awful lot of force; in fact, I would guess that the torque goes up to automobile specs.

Is muscling up right? Can someone be a bit more technical and describe how those fittings are supposed to be handled?

  • 3
    Did you use thread tape or dope? Is there a flexible line? It normally cant't hurt anything trying too muscle it tight. If you have the tank hard plumbed (no flex line ) you could break the pipe or fitting but you would need to take it apart any way to fix it if you can't stop the leak.
    – Justin K
    Sep 30, 2013 at 23:51
  • I used tape. The leak is from the nipple to tank connection. I'm using flexible stainless connector hoses.
    – chad
    Oct 1, 2013 at 18:30
  • You're right the be concerned about applying too much force. Pipe threads are tapered and if you apply too much force the wedge-like action can split the fitting you are driving the nipple into - that can be expensive when it is integral with the water heater.
    – dlu
    Feb 10, 2018 at 4:02
  • Why you would want to attach your nipples to a water heater is beyond me but whatever blows up your skirt. Personally i like to use adjustable nipple clamps that can be muscled up to whatever pressure you desire. I have used tape but pipe dope just sounds weird, but if you have leaky nipples it is worth a try.
    – Alaska Man
    Apr 29, 2020 at 16:31

2 Answers 2


For most threaded connections, first hand-tighten and then using a wrench, tighten in quarter-turn increments. If it leaks, give it another quarter turn. You shouldn't need excessive force with a wrench to tighten it.

For anything other than compression fitting, use Teflon tape and/or pipe dope on the threads.

Make sure that it is not cross threaded. If you need excessive force from the beginning, there is a good chance you have cross-threaded it (assuming the correct thread type).

  • 2
    There are a couple useful questions that will help you determine when paste dope and/or tape dope should be used, and to figure out which goes on first.
    – Tester101
    Oct 1, 2013 at 10:41
  • I don't think I have a union. That's something you use when you are soldering to the copper directy instead of using a flexible connector hose, correct?
    – chad
    Oct 1, 2013 at 18:30
  • Thanks for the link Mike. More useful to me is a functional description of the purpose of the thing; that's just how I think about stuff.
    – chad
    Oct 2, 2013 at 15:36

That happened to me once.check the washer inside the flex line. You may have damaged it. It can be replaced or get a new flex line. I believe the water in the well is actually running down. If you tightened it with that wrench. It is distorted. Just a thought

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