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I live in a climate (Kansas City) that has freezing temperatures a few times each winter, sometimes for several days in a row, and I'm contemplating a project to use my sump pit and air-conditioner condensate water to irrigate the lawn in the summer.

I will need to pressurize and push this water out of the basement. The sump pump that came with the house goes up above the concrete wall to the wooden siding to exit the house, then back down underground to run away from the house. i know I will need to arrange a stronger pump to achieve the 20-40psi that runs the sprinklers.

It always struck me as a poor idea in a freezing climate: to have a pipe containing water in the air outside.

If I do my project, I'm thinking I will drill through the basement wall 12-18" below grade, and tie in a pipe to my sprinkler mainline that I will feed from a high pressure pump in the basement. I'll tar around both sides of the pipe before I backfill.

But are there any problems with drilling through the concrete? Watching out for rebar I suppose too.

Is there a reason (other than not wanting to rent a concrete drill) that the original builder didn't have a single hole through the foundation walls, but drilled through the wood instead? (Actually, the potable water comes in through the floor of the basement, a good 6 feet below grade)

I generally would prefer not to see any thing coming out of the wall of the house above ground any way aesthetically. But with the additional concern of freezing, I would think being below grade would reduce risk of that.

And I could also use this pipe to blow my sprinklers out in the fall with a compressor in the basement instead of hooking one up outside I bet. Perhaps though, I would want to run this 'feed' to the existing main valve box of my sprinkler system, not to a midpoint in the trunk line, but that's more work excavating....

And I guess also, what kind of pipe/hose material should I use, suitable for direct burial, and capable of passing water and compressed air? I'd imagine 50psi typical max pressure, but I'd want it to be rated to at least 200psi just in case of a mistake while blowing the system out.

NOTE: Some sprinkler systems receive their water from the house, Some receive it from the meter directly. In my neighborhood, there is a split-off in the meter can and one line goes into the home, and the other into the sprinkler system. The sprinklers do not today, receive water that has gone inside the home.

There is a backflow preventer in the main sprinkler valve box, and if I send pressurized water/air from the sump pit, it will of course be connected to the DOWN stream of that backflow, so my coffee doesn't taste like sump water. I'm even tempted to re-route all water to the sprinklers if I do this, so that its no longer feeding from the meter directly, to make that kind of backflow even less likely to happen.

Thinking about it now, I think I'll at least shut off and tag-out the incoming valve in the yard as long as this system is in place, and plan to provide all water through the basement so I'm not depending on a backflow valve I only look at once a year.

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    What is your frost level there. Frosty ground will freeze water just as well as frosty air. The high loop above the wall probably drains the sump pump line well, so water does not freeze.
    – crip659
    Commented Jul 16, 2023 at 15:46
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    Does the irrigation line exiting the house go to a distribution manifold that needs to be winterized every winter? I am not sure of the need to be concerned about pipe being strong enough to hold 200psi, since it is all static pressure beyond the pump, which is presumably in the basement? Unless there are valves beyond the basement wall that will require the line to hold at least street pressure..... This small bit of info will affect my answer.
    – Jack
    Commented Jul 16, 2023 at 16:00
  • Hole in foundation means risk of yet another leakage point, if water table rises that high or ground next to house becomes soggy after being rained upon
    – keshlam
    Commented Jul 17, 2023 at 0:04
  • Foundations handle high water table better than you may think. Soggy dirt doesn't weigh that much more than damp dirt;; you get leaks (if there are any ways in) long before you get crush or lift issues.
    – keshlam
    Commented Jul 17, 2023 at 18:46
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    Holes in walls aside, what is the water supply plan here? Your sump will produce lots of water during and after rain, and none during dry spells when you need it. Your A/C condensate does not produce enough water to make this a worthwhile project. Does your plan include storage of rainwater? How much?
    – jay613
    Commented Jul 17, 2023 at 18:46

1 Answer 1

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You have many questions, but I'll answer the question in your title:

  1. Holes invite leaks.
  2. Holes invite fractures in the concrete.
  3. Concrete is harder than wood, so you always drill through wood given an option.

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