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cold water supply line blockage. How do you clear it?

Posted by dreams11 (My Page) on
Tue, Mar 11, 08 at 4:10

I Have a 1930's house that has a water supply problem in the second floor bathroom. The cold water supply to the sink has a blockage but the bathtub has a good flow. the hot water is fine to both.

I took the on/off valve off of the pipe to make sure it wasn't the valve or the the faucet. With the main water line on that pipe still produces a small trickle. All other
flows in the house are fine. This sink has not been used for many years due to a large crack in it. I decided to replace the sink but now the water flow problem.

What options do I have to try and clear the blockage or am i out of luck and the pipe will have to be replaced. (ripping walls out ect yikes!)

thanks in advance.


Follow-Up Postings:

RE: cold water supply line blockage. How do you clear it?

Assuming you have galvanized piping, the only answer would be to replace it. When you do replace it you will probably find that the inside diameter of the pipe is only a pin hole.

Good time to do a bathroom renovation.

Dan Martyn

RE: cold water supply line blockage. How do you clear it?

Here's a trick that we used in an area that had hard water with resulting build up in the pipe....if it works it could get you by for a few years......we made up fittings that would either screw directly on to the pipe or to the faucet aerator. In this fitting we used a male and female quick connect like you would find used in air tools.
We would hook a compressor up to this, turn the water on and blow air into the line. With the compressor still running quickly disconnect the "quick connect". Water and grit will blow out of the will be like sandblasting so you have to be carefull of your eyes and anything elset that could be damaged. We would do this over and over for 20 or 30 minutes if necessary. Each time we would see and increase in water flow. When it got to the point of being satisfactory, we'd stop.
You will find that with lots of minerals in the water this problem will develop with pipes that are not used for a long time. We had this in old mobile homes where the water was shut off and drained for the winter. With the ones that were not shut off, we never had a serious problem.
It will take a little poking around to come up with the fittings to make the tool that I've described above, but it should work.
We once had a straight main, galvanized supply coming into a house that had the same problem. We took off the valve and ran a small electric snake down the line. The water and grit blew out like you wouldn't believe. We did that about 15 yrs. ago and I think that supply line is still feeding the house. This last one is probably not going to be accepted by local authorities if you have a munnicipal supply:-)

RE: cold water supply line blockage. How do you clear it?

thanks for the reply guys.

I'm going to try the compressor trick but if that doesn't work I think I will try and run a flex hose from the toilet supply (20 inches away) thru wall to where the original sink supply stub out is.

How do I unscrew the 80 year old stubout and 90 degree fitting from the blocked supply line? If I have no choice but to cut it is t possible to cap it without threads? what options do I have? ( I need to take the old stubout off so I can attach a piece of pipe to the flex line and have the new piece of pipe connect to the on/off valve so it all looks original from the outside)


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