I replaced the innards of my toilet with something like this, all went well. The toilet works, etc. It involves undoing the water pipe, replacing insides of toilet, then screwing the water pipe back together. I had no problems, but after finishing everything up I'm still getting a small drip from the pipe (underneath toilet base, near shut off valve).

The instructions say to only tighten the plastic pieces by hand, I've done that as much as I can. But there's still dripping from the piece that connects the toilet and the pipe.

Any tips? The instructions make it clear not to tighten with tools or use sealant. It did not drip before I unscrewed it and put it back, and there was no sealant. Do I just need to tighten it more?

Edit: Here's the pipe, it's not plastic sorry. The top black piece is new and came with the parts I bought, the bottom piece is old.


  • Have you tried loosening the mounting nut (the black plastic nut), and making sure the gasket (red washer at the top of the threaded portion) is properly seated? Did you install the mounting nut in the correct orientation (the beveled side should be up)?
    – Tester101
    Feb 6, 2014 at 17:43

3 Answers 3


The toilet connections shown depend on rubber gaskets to make seals. These seals likely need replacement. In addition, I see that PTFE (white colored) tape was used. It should not be used for these fittings (or any compression or flare fittings), and can cause leaks.

Disassemble the connections. The top leak is likely caused by the washer (inside the toilet tank) not being seated correctly. The gasket should have come with the replacement fill valve. The tank should be cleaned at the location where the gasket sits. I can't tell for sure, but the nut holding the valve onto the tank looks a little bit undersized. It should completely cover the hole in the tank.

The metal flare tube also needs a washer in order to mate with the fill valve. This washer should be replaced. I would tighten it hand-tight plus 1/4-1/2 turns. In addition, the nut should be cleaned of the debris visible in the photograph.

Tubing connections

Another reason could be that the tank was cracked. Sometimes, hairline cracks are very difficult to see, but are able to produce leaks.

  • Yah, your leak is probably from the top washer. Did you carefully clean the tank where the washer sits? Did you tighten it per directions? Rubber needs hand tight plus 1/2 to 1 extra turn. No more. If you do too much it will leak (because you crack the rubber).
    – Ariel
    Feb 7, 2014 at 17:39

There is a good chance, especially if the existing pipe is old, that you may need to either replace the pipe with a new one and new seals. If the pipe was metal you could probably get by with just replacing the fake rubber seals in the ends but from what you've described it sounds like the connecting pipe is made of plastic.

Over time the seals in the plumbing fittings will harden as the plasticizer leaves the material. The hardened seals also take a "set" in their shape from the long term position. When you come and undo these connections and then reattach them the "set" does not perfectly fit to the plumbing fitting surfaces in its new possibly altered position. The hardened nature of the seals also means there is loss of compliance for the seal to smudge down tight on the mating surfaces to re-seal the connection.

Plastic connecting pipes can take on a malformed shape that is not optimum for the shape of the seal. Think of the pipe being slightly out of round being used in a fitting and with seals that are designed for a totally round pipe. This can lead to leaks when joints are taken apart and then re-assembled. Sometimes a new seal that is nice and compliant can be used with out of round pipes and make a good seal.

In the long run it is often the simplest to just replace the leaking pipe with a new one. I like to use the flexible type that are sheathed with the woven stainless steel mesh.

  • I did replace the plastic seals (one came with the parts) both both pieces still drip.
    – Zeno
    Feb 6, 2014 at 14:48
  • Don't try to fix it, just replace it. A new flexible stainless steel braided hose is less than $10. The new fittings are very reliable as long as they are not overtightened. (Usually hand tight)
    – mfarver
    Feb 6, 2014 at 15:27
  • 1
    If you are getting a leak on the fill tower joint you either didn't clean the mating surface well, it is too rough, or the rubber washer at the base is not working well. (Overtight, maybe).
    – mfarver
    Feb 6, 2014 at 15:33

I just had same problem, after many tries, realized it was not the water line, but leaking from tank. So I dried toilet tank completely, making sure it was completely dry after I drained it, wiped bottom of tank with a dry towel and then let it air dry for a while. Put fill valve back on and screwed it tight. Then I added a few glasses of water from the sink directly to the tank and waited 15 minutes to see if leaking from tank and was good. Then screwed water line on and no more leaking.

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