Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

How to stop water when soldering pipe

Hey guys so I am installing a water heater and saw a leak on the main line. I turned the water off to the whole system but I can't solder because water is still coming through. What are your techniques for this problem?


  • Ironman
    Ironman Member Posts: 7,221
    edited October 2020
    Moist white bread molded into a tight ball and packed into the pipe firmly. The water will dissolve it when it's turned back on.

    Try to get it a couple of inches away from the heat.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • hot_rod
    hot_rod Member Posts: 20,725
    A trickle or a stream. The bread trick may work unless you have a stream and some pressure.

    If it is copper or galvanized, a freeze cuff, pex can sometimes be pinched with a special vicegrip tool for that purpose.

    Press tools are another way to add or replace a valve with some flow in the pipe.

    I've also used compression fittings as well as the Sharkgrip, in a bind. You can buy ball valves with press, grip or compression fittings at the box stores.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • unclejohn
    unclejohn Member Posts: 1,833
    If you are going to add a new shut off and the bread won't suck up the water you can stuff a rag into and through the valve and solder right quick.
    Glenn_16Dave T_2
    EBEBRATT-Ed Member Posts: 14,495
    If it's just water in the pipe and not a valve leaking by sometimes you can take a hanger or two off and let the pipe sag so the water will run out.

    If your trying to patch a leak just cut the pipe get the water out and put a coupling in
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,373
    Jet Swet, press fitting, or have someone come over with a curb key.
    JUGHNE Member Posts: 10,898
    What has worked for me is to loosen the fitting on the water meter outlet and catch the water stream in a bucket or pan. Or if you're lucky have a floor drain close.
    This will get the main pipe dry enough to solder on.

    You should replace the main service valve also. You would need to shut off the curb stop outside for this.
    I usually put a hose bid on the main right after the water meter. This is handy for any future work to drain back piping.
    Solid_Fuel_Manrick in Alaskamattmia2delcrossv
    EBEBRATT-Ed Member Posts: 14,495
    If you loosen up the meter connections to drain water put a pair of jumper cables across the water meter first. Then remove them when the fittings are tightened
  • 426hemi
    426hemi Member Posts: 80
    Don’t attempt without shutting off the water, if you don’t have a curb key get one there under a 100 bucks  imagine the damage if the supply line let go and you had to wait a hour plus to get someone to come shut it off cheapest insurance you can buy
  • SlamDunk
    SlamDunk Member Posts: 1,508
    Sharkbites in a pinch. (Always keep a variety of those in the house! ).

    Take a breather then try the bread thing or call a plumber with a propress or a freezer.
    JUGHNE Member Posts: 10,898
    Or you can install a union, the 2 pieces allow you to push the pipes up, keeps the end of pipe open for steaming and then you screw it together.
  • Solid_Fuel_Man
    Solid_Fuel_Man Member Posts: 2,644
    I've used the bread trick many times with good success. Its suprising how many slices of bread you can stuff into a 3/4" copper pipe! 
    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!
  • Glenn_16
    Glenn_16 Member Posts: 14
    Remember once asking the client for a piece of bread and she asked if I wanted a sandwich!
  • NoelAnderson
    NoelAnderson Member Posts: 47
    Before using white bread, I will use my large shop vac to suck out most of the water in the line.
  • mattmia2
    mattmia2 Member Posts: 8,834
    That is good for draining water out of a low spot in a line if you don't have compressed air available as well.
  • Intplm.
    Intplm. Member Posts: 1,603
    Vent the system from a high point faucet and find the lowest point to drain it like a low-level sink or outside faucet. Leave these on and allow time for the water to drain. Be sure that the valve to shut off the water is tightly closed. You can use bread stuffed into the pipe if very little water is trickling out.

    You can also use a tool called a jet swet pictured here. Be sure to purchase the correct size.

  • dopey27177
    dopey27177 Member Posts: 887
    Back in the day there was a tool that allowed you to stop water flow. I used this tool to replace main valves up to 11/4". You inserted the rod with several rubber stops that when you operated the expansion nut it create a seal against water pressures up to 80 psig. This tool is no longer available but a better one can be purchased. It is more versatile a little pricey for a home owner but great for a service contractor. See attachment.