Routing downspouts to an outdoor sump


Old 08-12-17, 08:55 PM
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Routing downspouts to an outdoor sump


I've got two downspouts that are tied together underground. The downspouts are on a wall that has the in-ground pool 5-8 feet away from the house, that spans 40 feet or so, necessitating the go-around. They're also tied to a yard drain that's in a lower elevation area that collects water when it rains (and itself isn't more than 8 feet or so from the house, but around the corner from the downspouts). Finally, the whole thing connects to a PVC pipe run to the alley where it should drain. The pipe doesn't exactly run downhill. The previous owners explained that at some point they installed some sort of in-line pump with a water sensor in the PVC line to get the water out. There's an AC cord that runs into the ground but I'm sure this thing died in the distant past. I don't think it's any sort of sump system as it's completely buried under grass and dirt. Sticking a running hose into either of the downspout ground entry points gives me water coming back up this one drain.

A little more background- the yard is very uneven, and has shifted over the years such that the previous owners had a number of yard drains installed to catch all the low points. The lines connecting the drains are PVC but at some point transition to lesser pipe that I know to be partially clogged and/or had roots gone through (I've spent quite a bit of time trying to snake up some heavy drain tape as well as running water through each of the drains to try and map it out).

Long story short, the spot where the drain is that is tied to the downspouts, is the lowest spot, collects the most water, and is closest to the house- so I've pondered installing an underground sump in the spot where the drain is. Now that I know all of this is tied together, this sump would handle two downspouts' worth of rain in addition to all the groundwater that collects. Any reason not to do this? I'd need to either make sure that PVC line gets cleared (and is solid), or install a new line.

Thanks for reading!
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Old 08-12-17, 09:23 PM
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There was no reason to tie the downspouts together or with the PVC. Everything should have been separate, in the first place. Installing a sump pump won't correct it, IMO. I would separate the drains & install dry wells.
Old 08-12-17, 09:53 PM
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Tied in or not where do they drain to?

You want everything sloped away from the house so that you dont have any external pumps, honestly this is the first time I recall anybody stating they had some type of pump on an external drain!
Old 08-13-17, 04:04 AM
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A downward sloping pipe and gravity is your most reliable drainage method working toward that would be my first choice. If you really want to pursue the pump idea your first step is to investigate the power issue as the pump is going to require electricity.
Old 08-13-17, 05:00 AM
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You need to correct the place where the underground pipe is not exactly sloping downhill. You could just go deeper and deeper until that becomes impractical and then install a dry well, by this time you are at least a little ways from the house. You are not going to introduce the drain pipe into the bottom of the new drywell but instead the dry well must be dug down further from where the drain pipe will enter. If this dry well ever overflows (above the level where the drain pipe entered) you will need to put a sump pump in it to elevate the water to a nearby perhaps newly installed collector branch of more underground drainage pipe that is closer to the surface and going downhill and further away from the house from there.

Another alternative is to discharge the downspouts onto the surface instead of underground. Regrade the land so the water flows away from the house. This gives more downhill slope to get past the low point and over to the main underground drain system with or at least gives you a little more vertical drop for the water to run away from the house with.

A sump or dry well right at the foundation has little value. You will have needed to mechanically elevate (pump) the water to the next section of drain pipe before that water has made any progress away from the house. You might then need a second sump and pump to elevate the water again to give it more downhill oomph to complete the trip to the alley. In addition, if a sump right at the foundation is not watertight (doubles as a dry well or springs a leak) it exacerbates water seepage into the basement.

Last edited by AllanJ; 08-13-17 at 05:32 AM.
Old 08-13-17, 12:38 PM
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Thanks for all the replies!

We're in Dallas, TX. Slab foundation without a basement. We've got high % clay soil so my limited understanding tells me a dry well wouldn't work too well.

Water drainage (should) ultimately go to the street or to the alley. I understand why they tied the downspouts together (to be sure, it's the underground drain pipes that are tied together)- and, at this point, because of how the pool really blocks all straight access to the alley, short of knocking out pool decking, there's only one side of the pool to go around, so the lines would run parallel out to the alley once they clear the side of the pool (but yes they should have been dedicated lines).

The house is 35 years old, and if the lines ever did run downhill, they don't any more (because of shifting), and guessing that's why the previous owners installed whatever pump they've got in-line down there. Or maybe the house was graded correct to begin with Re-grading isn't really an option as the alley ground level is at (if not above) the same elevation as the soil line at the house.

So I think I'm stuck having to pump the water up and out in some form or fashion.
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