It's a southern California structure built around 1970. It has these cellar storm doors, but it's not the access to the crawlspace and appears to have a capped off gas? line. What is/was this?

[Update] Some additional notes...

  • The part of the house with the windows is original and the section to the right in the image(s) is an addition added in the late 90's IIRC. The reason the roof lines make it look like it's the other way around is that the addition had its roof overlap the original.
  • Inside the cavity there is a metal U-channel (visible in the photos attached to the foundation stem wall) which slopes down from right to left. Perhaps that was part of a bracket system for some equipment/tank?
  • The black cable at the bottom of the cavity is an RG-8 coaxial cable probably from an old cable or satellite TV install and they just used the location as a convenient way to enter the crawlspace?

[Update] Original owner located

Turns out the original owner of the property installed a water tank there that was plumbed into the gutter system to collect rainwater. It was then pumped out to irrigate the landscaping, which explains the brackets (where the tank was attached), the wiring (power for the submersed-pump), the non-weatherized doors (because the tank itself was weather-proof), etc... So much respect to the author of the accepted answer who figured this out with way less information than I had!

enter image description here enter image description here

  • Seems too small to be of much use, so would think an access hatch for working on underground(now?) water/gas line. Doors do not seem made to keep out nasty weather.
    – crip659
    Jan 13, 2023 at 1:48
  • Is the part of the house in the left an addition?
    – Jon Custer
    Jan 13, 2023 at 1:48
  • 1
    Normally shouldn't see union on a gas line in an enclosed space. Technically I think they are permitted if outside of a home and outside of the foundation area, but... You sure that's not an old water line? Jan 13, 2023 at 3:35
  • @JimmyFix-it good point on the union
    – P2000
    Jan 13, 2023 at 5:08
  • access to your crawl space will be inside your home, probably in one of the closets, as a cut out in the floor
    – Traveler
    Jan 13, 2023 at 6:03

1 Answer 1


This is possibly access to a water cistern. Such a cistern could be an underground tank under house/yard, or its walls could be formed by brick & cement, thus located under the house and integrating with the house foundation. Based on the updated to the answer, the former was the case.

Then at some point in time the cistern cavity was decomissioned and backfilled.

Since this left part of the house is the old part of the house, there my have been a porch here, and this was the access hatch to the cistern - under the porch.

The pipe is likely not a gas line (as debated in the question & comments) but a water pipe to fill the cistern, or to connect to a pump to serve the house or water the garden.

enter image description here

Ref: https://www.oldhouseweb.com/blog/cisterns-historic-water-convservation/

  • 4
    and the down votes without comment or alternative answer are based on what?
    – P2000
    Jan 13, 2023 at 2:54
  • 1
    Water cistern might make a lot of sense... the line there which comes from the opposite direction of the house might be a water line to bring rain water to the tank? Jan 13, 2023 at 6:57
  • 1
    Down votes are probably because of "Not really an answer, just a guess." Misguided, IMHO, but that's probably it...
    – FreeMan
    Jan 13, 2023 at 13:24
  • 2
    @FreeMan edited. Feeling vindicated today...
    – P2000
    Jan 13, 2023 at 14:28

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