I'd like to replace this old toilet copper supply line with a more flexible braided supply line. The problem is that I can't find one with the right connection to the water supply valve.

Current (copper) connection: Picture of current connection

The two closest replacements I have found are:

1) BrassCraft Model# "B3-12DL F"
Description: "1/2 in. Compression x 7/8 in. Ballcock Nut x 12 in. Braided Polymer Toilet Connector"

2) BrassCraft Model# "B8-12DL F"
Description: "1/2 in. FIP x 7/8 in. Ballcock Nut x 12 in. Braided Polymer Toilet Connector"

Images of BrassCraft models: enter image description here

By my measurements, the interior diameters are:
- Current connection: 11/16 inch
- BrassCraft model B3-12DL F: 10/16 inch (1/16 inch too small)
- BrassCraft model B8-12DL F: 12/16 inch (1/16 inch too large)

The connection types of the two models is different (one is 1/2 in. Compression and the other is 1/2 in. FIP). I don't know what type is necessary to replace the old line (maybe neither of those), but the FIP (Model B8-12DL F) looks more similar to the existing connection.

If anybody has any insight regarding how I can connect a new flexible braided supply line (without replacing the water supply valve itself), I'd greatly appreciate it!

  • That valve has a compression fitting on it, and I doubt you'll find a hose that fits it. And, why do you need a flexible hose? Are you expecting your toilet to be mobile? May 16, 2016 at 11:42
  • Thanks for the reply. The old copper line is worn out and starting to leak (at the rubber gaskets). So I need to replace it somehow. Also, the whole toilet shifts slightly when sat on, so I'd like a flexible hose to prevent damage at the water supply valve and the toilet fill valve. At some point the whole toilet should probably be replaced, but in the mean time I'd like to stop the leaking and prevent additional damage (while still having a usable toilet).
    – cpotter
    May 16, 2016 at 14:06
  • Your shifting toilet is a bigger problem waiting to happen, with the possibility of the wax ring seal breaking and you ending up with sewage in your subflooring. And, compression fittings don't use rubber gaskets, so perhaps they aren't compression fittings (although they really should be). Properly installed compression fittings should be very reliable, absent movement. May 16, 2016 at 14:15
  • @Daniel Ok, thank you. I've looked into how a toilet connects to a waste pipe and I see how the wax ring seal could be damaged. For the time being, I've installed toilet shims to stop the shifting.
    – cpotter
    May 18, 2016 at 0:45
  • @Daniel Regarding the water supply line / valve, I think you're right that it will be difficult to find a line with the proper connection. Currently it's only leaking a few drops of water each day and they evaporate before they reach the floor. I plan to let it go for now. I don't think it can lead to a sudden failure with flooding. Please let me know if you disagree. When I'm ready to attempt it, I'll shut off the main water supply and replace the supply valve with one that has a standard compression connection.Thank you for your input!
    – cpotter
    May 18, 2016 at 0:46

1 Answer 1


That shutoff looks super old. I would turn off the main shut off, cut off the old shutoff and get a push-fit shutoff and toilet supply line. The new shutoff will be about $10 and the supply line will be about $5. You will also need a copper cutter or hack saw and possibly a meter key and pliers.

  • While you're at it, pick up a rubber toilet seal to replace the wax one. If your toilet is moving, wax seals are more likely to fail. Try to fix that problem, too. May 6, 2018 at 3:39

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