I turned off the water to the house to change the valve on a toilet supply line. All of the faucets and the tub were cut off but water kept coming out of the toilet line when I removed the valve. It just kept coming but not at high pressure. The water was warm and the water heater is nearby. Its a slab foundation but I don't think the house has been replumbed thru the attic, and wouldn't such a gravity drain off go to the tub and faucets also? It's a mystery (to me at least)! Any ideas.

Have Wrench, Not Plumber

  • Are all the faucets open (turned on)? The water will drain to the lowest open fixture. Is there a local shut off at the toilet?
    – Tester101
    May 29, 2011 at 13:14
  • Did you drain the tank first? Sep 1, 2011 at 17:13

1 Answer 1


Unless you have some phantom water supply, the water you are seeing is standing water from pipes higher than the ballcock valve you are trying to change. Is there a hot water mixing valve connected to the cold supply for the toilet? This is common to supply warm water to a toilet to control sweating. If so, is the water heater at a higher level than the toilet valve? If this is the case, try shutting the supply to the mix valve. With all that said, you may have to simply put a collection vessel under the offending tubing and let the water drain out. It will stop eventually after all the standing water above it has drained off. If you open the faucets on other fixtures located higher than the toilet, the draining will happen faster. Of course, an obvious check would be to assure the main shutoff is completely closed, and not leaking by.

  • This is the case with my house (single-level slab) as well - I have to open the tub spout and it takes forever to drain the standing water. I'm not clear on the mechanics of it, but I have to shut off the out valve for the water heater as well as the water main. The plumber who installed our water heater a few years back got tired of waiting for the water to drain and plugged the dripping pipe he was working on with a chunk of bread. It stopped the water long enough to solder a joint, and when the water was back on, the pressure broke it up with no problem. Jun 6, 2011 at 11:18
  • 1
    It's worth mentioning that connecting warm water to the toilet is only common in SOME climates. Here in Colorado, you only see cold water supplies to the toilet. Mar 5, 2014 at 6:11

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