I have a 1953 ranch with daylight basement. Pictured below is the point where (I believe) the water main enters the house horizontally (water meter is out in front lawn at ground level, aligned with this entrance). Upon entering, there is a T branch. Upwards pipe goes to a shutoff valve, while the downward branch disappears into the floor and is upstream of the shutoff. I can't figure out why this was done this way. It's possible I have it reversed and that supply comes out of the floor and then goes back out of the house at the T, again before the shut off valve. I am trying to track down the many possible causes of a damp floor in this area and would like to understand why this was done this way before going further. Thanks in advance!

UPDATE: I have called a plumber (I don't want to DIY myself into a bigger mess on this particular project) and will update once I get an answer.

Main house water supply, coming in to T either from the floor or from midpoint

enter image description here

Edge of meter box, with house in distance showing hosebib - supply to this hosebib shown in image 4

Top of main line showing branch to hose bib with separate shutoff

Water meter

House-side outlet of water meter, angled into ground

  • Where you are would probably affect the likely entrance point of the water supply (due to frost depth.) Though merely having an outside meter implies shallow or no frost depth. There may be an additional shutoff at the meter, though this is certainly an odd arrangement.
    – Ecnerwal
    Commented Jun 18, 2019 at 16:44
  • I'm in the Pacific NW USA, so I think "shallow or no" frostline is about right.
    – David J
    Commented Jun 18, 2019 at 16:55
  • 1
    My vote is the water comes from below and the branch going through the wall feeds something else. Are there any out buildings or water spigots on that side of the property ? or another pipe coming out of the floor in the basement somewhere ?
    – Alaska Man
    Commented Jun 18, 2019 at 17:08
  • Could the valve be the shut-off for the house only? The line that Tees off could be to supply the outside faucets. If this a pier-and beam, have you looked under the house to see if there is a cutoff there for the line going through the foundation? Commented Jun 18, 2019 at 17:10
  • There is a water spigot near there on front of house but it is fed by a branch downstream of the shutoff. Interestingly, there are two spigots on the back of the house that have been disconnected (capped off inside the wall from what I can tell from the one I can access) and I am starting to wonder if it is a feeder line for those. There is one additional hosebib on the house that looks newer and is affected by the main shutoff. There are no additional outbuildings.
    – David J
    Commented Jun 18, 2019 at 17:12

3 Answers 3


And the answer is.... water line comes in horizontally. BUT, a shocking discovery made by my plumber while sorting this out. Somebody else in the past had the same idea as me and started to remove the downpipe, then abandoned the effort. They made a horizontal cut into the pipe below the T, from behind. It was not easily viewable from the front. I put a feeler gauge into the cut slot and it appears to be DEEPER than the pipe wall thickness. Basically, it's just rust and gunk that has kept the water from exploding out of that slot. I've encountered my fair share of home improvement crime scenes over the years, but this one is right up there... a glob of rust away from disaster.

Finished Job Pipe cut by previous jacka** of all trades

  • +1 for "home improvement crime scenes." So, it's still a mystery as to what the down leg is/was for?
    – Tim Nevins
    Commented Jun 21, 2019 at 19:49
  • @TimNevins, yes, have not formally solved the downleg question, although I have high confidence it's a run to the two decommissioned hose bibs on the back of the house. If I get motivated (and find a long piece of wire) I might do a conductivity test between the now disconnected down leg and the capped off supply to the hosebib I have access to.
    – David J
    Commented Jun 22, 2019 at 16:49

Does the property have any underground irrigation system -- sprinklers for a lawn, for instance? If so, is that system fed with potable water?

It might be that the supply from the meter rises from the floor and the branch going through the wall supplies the irrigation system. One would hope for a shutoff valve in that branch. Since no valve is visible on the branch going through the wall, maybe there's also a stop-and-waste valve buried nearby outdoors. The only sign visible on the surface of the ground might be a 3 or 4 inch diameter pipe going straight down, hopefully with a lid to keep out debris.

  • Condensation for one .The old pipes are breaking down. Would be my guess. For water stains. and is the floor sealed good.
    – user101687
    Commented Jun 18, 2019 at 18:07
  • No sprinkler or irrigation system that I know of. No sign of any valve or control box outside the house in this area. It's a fairly straight shot from the meter box in the lawn to the house and were I betting, I'd put money on the middle horizontal line being the main. Might do some excavation in the flower bed in front of the house to see if I can find the line or any buried shutoff.
    – David J
    Commented Jun 18, 2019 at 18:09
  • @RobertMoody floor is unsealed - this is actually the genesis of this whole effort. I cleaned out this room and scrubbed floor in order to prep for epoxy paint. The area in question was wet before (in appearance - no puddling) but we had to do some cat cleanup and I assumed it was that. Now, I've scrubbed, squeegeed and shopvac'd the whole area and had a fan overnight. Most of the rest of the room is dry now except for this area, which still looks damp. Definitely suspecting breakdown of underground water pipe.
    – David J
    Commented Jun 18, 2019 at 18:16
  • Your lucky you even get water out of those old pipes. The rust one day may break off and no water at all.Sock away and some day add new line.
    – user101687
    Commented Jun 18, 2019 at 18:23
  • Sock away is a term my dad used to save your penny for a rainy day.
    – user101687
    Commented Jun 18, 2019 at 18:25

You have a main shut off . And tee fitting after that . Steel pipe is old or no good. and you may have a leak. Because in slab. disconnect run new pipes over head to house done.

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