enter image description hereI'm working on a bathroom faucet that has been dripping. I turned off both shut-off valves (one to the hot and one to the cold). However, I also noticed a yellow lever on a pipe that feeds into the cold water supply pipe. In other words, three pipes come from the bottom of the sink cabinet (the drain pipe exits through the side of the cabinet), two of them combine before they go to the cold water side. One of those pipes has the usual shut-off valve but the other one has a yellow lever. It looks like the main shut-off valve near my water heater. What is this yellow lever for? Thanks for your help!

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    Could it be the feed to the toilet? Try turning it off and see if toilet doesn’t fill.
    – Tim B
    Jan 23, 2020 at 23:37
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    It's a quarter turn ball valve. In the pic it's in the off position, has it always been in that position or did you close it? Jan 24, 2020 at 0:16
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    It's always been in the off position. I did turn it on and heard moving water, so I turned it off because I didn't know what it was doing. What does it do?
    – Josh
    Jan 24, 2020 at 0:19
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    We do not know. What else is in that area? can you trace the pipe? Your best and only option
    – noybman
    Jan 24, 2020 at 1:12
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    It might have something to do with a hot water recirculation system (presumably not working or decommissioned) or it may just be a cold feed to something that's not been getting water for a while...
    – Ecnerwal
    Jan 24, 2020 at 3:08

2 Answers 2


Figured it out! The upstairs bathroom valve controls the outside spigot on the back of the house. The valve in our master bathroom controls the outside spigot on the front of the house. Thanks for all the help and comments.

  • 2
    Since you know for a fact that this is the correct answer, you should click the "accept" checkmark, to indicate that your question has in fact been solved. Jan 27, 2020 at 6:26
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    Great. Now put a label on it! :)
    – bishop
    Jan 27, 2020 at 17:11

We can not tell you where it goes or what it is for specifically.

We can tell you what it is, It is a 1/4 turn valve, with it turned parallel to the pipe it is open and with it perpendicular to the pipe it is in the closed position.

My guess is it is a cold water feed to another fixture ( hopefully, and not just open ended.) You say it was in the off position before you did anything,

Is there a fixture elsewhere that does not function?

Do you have access to the plumbing below the bathroom ?

Of the two cold water lines i would think the left is the supply line and the tee off to the right is sending water elsewhere. I.E. Turning the clear plastic valve to the faucet off does not stop water from going to the yellow 1/4 turn valve via the tee, verified by the fact that you get water from the faucet when the yellow valve is closed and the clear plastic valve is open. Turn both valves to the closed position and then open the cold water only on the faucet,( no water should be coming out ) next open the clear plastic valve ( leave the yellow valve closed ) and if the water starts flowing from the faucet then the left line is supply line to the faucet.

Further investigation will be needed to determine what the yellow 1/4 turn valve is supposed to supply water to.

A hot water re-circulation loop is a loop within the hot water plumbing.

  • "A hot water re-circulation loop is a loop within the hot water plumbing." -- not necessarily. A common retrofit is to use the cold water line for the recirc return. Plumbing it in this particular way would be odd, but not completely out of the question. Of course, there are dozens of other things it could be...certainly there's no reason to suspect hot water recirc as a likely candidate. But given the odd arrangement in the first place, it's certainly possible. Jan 25, 2020 at 7:02

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