I have two drains on the side of my house that have been filled in and no longer properly drain. I know they dont go anywhere because I just finished trying to unclog them with a rented drainage snake that I rented from home depot (and my neighbour actually told me the same thing!).

So, i'm wondering the best way to drain my gutters now. Should I:

a) break up the concrete that's on the sidewalk (side of the house) and re-do a french drain system or PVC?

b) Plug in the drain holes with concrete and angle them away from the house, to the other side of the sidewalk. Then, dig a trench from the back of the house to the front and install a french drain system.

c) something else.

enter image description here enter image description here enter image description here
A little history...

This was originally a carport that was closed in to make an extra bedroom. They built it with 2x4's running on the flat, and it had no insulation, and the siding went right down to the ground. When we took possession of the house we knew the siding had to be done, but not the entire room inside! What we found was rotten 2x4's, and a moldy carpet. We ripped it all up, re-built that wall and the siding (as you can see form the picture).

For the bottom of the wall, since we weren't ready to dig up the foundation and re-pour a 6" border, we put down 4x4's, peal-on-stick and we flashed it. Then, added roofing tar in between the layers and on the outside.

enter image description here

  • Is all of the concrete next to the house sloping away from the house?
    – DMoore
    Commented Sep 6, 2013 at 19:05
  • Wow! Excellent problem description and photography!
    – wallyk
    Commented Sep 6, 2013 at 19:33
  • @DMoore it's not obvious but it doesn't slope away so when water pools on the edge of the grass and concrete, it can make its way back to the house.
    – OnlyHumain
    Commented Sep 6, 2013 at 22:38
  • Well you need to fix the concrete issues. If its not sloped out it doesn't matter what kind of system you install.
    – DMoore
    Commented Sep 7, 2013 at 2:42
  • c) prior to addressing any big fixes, get some corrugated pipe as suggested in the answer below. You can hook this up NOW and keep the water running away from the house. This fix buys you some time to address a long term or more aesthetically pleasing repair
    – Freiheit
    Commented Sep 10, 2013 at 16:56

1 Answer 1


If I understand your issue correctly, what you're calling a french drain may actually more properly be called a drywell. A french drain pulls in groundwater and moves it somewhere else, while a drywell is a place to get rid of water underground. I think what you're talking about is something to pipe your downspouts into, and therefore I'd call it a drywell.

That said, one can construct a drywell in a similar manner to a french drain, by digging a trench and filling it with gravel and a perforated drain pipe.

The key difference to understand, however, is that if what you really want is a drywell to get rid of water, it may need to be bigger than you think. The rainwater doesn't immediately disappear into the ground surrounding your drywell, you need to provide some storage space so that you can hold the water while it can slowly leeches into the ground.

You may want to quickly estimate how much water you need to deal with. Estimate the square footage of roof drained by these downspouts, and then multiply by a rainfall amount (some sources say look up a 5-year 24 hr rainfall amount for your area, other sources say simply use 1"), to get an estimate of the volume of water that could be flowing out of these downspouts. It adds up quickly!

If you simply dig a hole and fill it with crushed stone, you may need a big old hole, as crushed stone can have a void space of around 40%, so you'd need a hole 2.5 times bigger than your estimated roof runoff.

Therefore, you may want to consider an underground structure for your drywell, rather than simply filling a hole or trench with gravel.

One such product is made by NDS, called the Flo-well. It's a nice compact solution that can sometimes provide a good match for an individual downspout. You can stack them or daisy-chain them if you need more volume. Dig a hole, place the well, and backfill with gravel then topsoil. Simply plumb your downspouts into the drywell with PVC. The flo-well provides open space to hold lots of water, and has holes in its sides to allow the water out into the surrounding gravel and soil.


Installing a flo-well

Or you could go with something even bigger if required, like some of the giant structures from Cultec that can hold up to 1200 Gal each, probably overkill for your application. These are like underground archways with open bottoms for the water to leech out of. Again, you'd dig a hole, lay a bed of gravel, place the chamber, and backfill with gravel then topsoil.

Cultec chambers

I have no affiliation with either of these suppliers, but have done some homework on this product space as I have a drainage issue of my own that needs solving on a tight, urban lot.

NOTE: If you are extra lucky and your property has some grade to it in just the right spot, it may be possible to simply run a pipe underground from the downspouts away from the house and have it come out the side of a hill to a place that you don't mind being flooded with rainwater. This is way simpler than a drywell. Just make sure to maintain positive drainage all along the pipe run (1/8" per foot or so).

drain outlet in hillside

image from www.askthebuilder.com

  • Yes, thanks Mac. I guess I am after a dry-well and not a french drain after-all. The water pools where the concrete meets the grass and if the rains are hard enough (we're here on the west coast) then it starts to pool back over the concrete towards the house again. Not good. I was thinking instead of running a french drain down the sidewalk, maybe move that water to a flo-well system in the backyard. I have a lot of room back there and in fact need to take care of another drain spout that's also pooling water between the concrete and grass. See updated pics.
    – OnlyHumain
    Commented Sep 6, 2013 at 17:39
  • If you do decide to plumb multiple downspouts into one drywell, make sure you maintain good steady pitch towards the drywell in all your underground runners, also make sure the system is sized appropriately, and consider adding an overflow provision such as a pop-up emitter in case a giant storm fills up your system.
    – mac
    Commented Sep 6, 2013 at 18:32
  • Thanks for the help! Since our area is sitting on a lot of river rock (from what I've been told) we could get away with a catch basin and grate that goes to a french drain system. That way we don't have to buy and install a dry-well as suggested.
    – OnlyHumain
    Commented Sep 6, 2013 at 22:41
  • @OnlyHumain: just a thought--why would you have pooling issues if the soil in the area was so great for drainage? Unless you're sitting on clean, crushed gravel (unlikely!), it will take some time for the water to leech into the soil. What you're calling a french drain is still a drywell, even if there's no "tank" built in, its job is still to hold water until it can seep into the ground. If you're going through the trouble of digging trenches and holes, do yourself a favor and make sure you've got enough holding capacity--could simply be a big hole filled with clean gravel if you prefer.
    – mac
    Commented Sep 10, 2013 at 16:22

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.