In our 2 story w/basement 90 year old house with original galvanized iron water lines, we recently experienced a serious water leak that destroyed a ceiling on the main floor. While searching for the source of the leak we discovered that in addition to the 1/2" hot & cold pipes that there was a 3rd pipe only 3/8" galv. iron that ran to other areas of the basement and we have no idea what it was for. It was the source of the leak so we just split a union in the furnace room and capped it. No more leak.

Our plumber had no clue what was the purpose of the 3/8" pipe nor do we or any one else we have asked.

Sure would like to know.

Any ideas?


Ed S.

what was it tied into in the basement? hot water or cold water?
I've never seen anything like that..

Perhaps a return line?

At this point I am going to go with the return pipe theory. We suspected connection somewhere to the hot water supply.

I know motels and other applications have a circulating hot water system. Perhaps at one time since this bath is upstairs and some distance from the water heater they installed some special faucets to recirculate hot water.

Still guessing

Thank you

If anybody else has a different opinion or idea, please continue submitting them



Edited 1 times.

It could be an old gravity recirculation line. Did you have to cap both ends of the pipe? Does it take longer to get hot water to the far bath with the line capped?