Any landscaping experts? French drain / dry well

The back corner of my yard floods every time we get any sort of rain. That area is a bit lower than the rest of the yard (and the neighbors’ yards), so it is obvious why it happens.

We hired a landscaper, with good references, to install a drainage system that would hopefully fix the issue. He dug two 30-foot trenches at a right angle, meeting in the corner where the biggest problem lies. Where the trenches intersect, he installed a dry well (I guess that’s what it is called, it’s basically a large plastic canister). He placed gravel and tubing along the trenches, connecting the tubing to the dry well. There was also plenty of gravel in and about the canister. Finally, he used the dirt from the trenches to raise the level of the surrounding area a bit.

Then, a few days later, we got some rain. Not a ton, but it came down fairly hard for an hour or so. We were left with a good 2-3 inches of standing water, not much better than before the fix.

We called the contractor and he came out first thing the next morning (this was yesterday). He said he knows how to fix it and will do so this coming week.

As I look at the area today, two days after the rain, the ground is still soft. It is muddy around the well (he dug it out a bit yesterday and removed the cap).

What puzzles me the most is that the dry well is now full of very wet mud. Is that to be expected? Is that how it functions? I would have thought it would be either empty, or have some amount of water in it.

Also, the dry well has a solid plastic cap. I would have expected some sort of grate to allow the water to enter freely (but then, here comes the mud, I guess).

Any input much appreciated.


There may be too many variables not mentioned that make it difficult for reliable feedback. Are the two 30-foot lengths of (presumably perforated) tubing intended to help water travel toward the dry well, or to help water dissipate away from it? If they are intended to spread the water out and help it soak into the ground, maybe you need more of them.

Is your soil not very porous? My yard is clay, and water absorbs into it very poorly. When I needed a drainage field, I had to dig several test holes, fill them with water, and measure the time it took for the water to drain away. That helped the workers figure out how big an area would be required for a “leech field” with lots of “laterals” similar to your two 30-foot drains. Did the landscaper do any testing like that?

How coarse is the gravel? Fine gravel is going to silt up and become ineffective faster than big coarse gravel.

Did the landscaper use landscaping cloth around the tubing or the dry well to filter out mud and slow down the rate at which it might silt up?

Is there a lower piece of land anywhere on your property? Is the street lower? We had a flooding issue on our property a few years ago and a french drain solved it entirely, with a gravel-filled ditch with a pipe that drains to a sloped lower piece of land on our property.

If this is the lowest point on your property, then I don’t know what to do, unless it can be filled-in or otherwise altered so there’s a gentle slope down to the street.

@Retzbu_Tox - Yes, the (perforated) tubing is intended to spread the water out and away from the corner area where it collects. Not that we need this corner to be always dry for any reason, we just don’t want it to flood with every rainfall.

The soil is porous, definitely not clay. He did not do any sort of testing beforehand. I’m not sure how course the gravel is, I guess I’d call it medium. Yes, there is landscaping cloth around the tubing.

@iiandyiiii - There is no lower area on my property than this corner. I hesitate to build it up because I don’t want the water diverted toward the house. Yes, the street is lower, and the french drain that you described was what we were expecting the fix to be.

More info: The contractor’s plan is to extend one of the drainage tubes and also create a corner rock field (picture a triangle of rocks in the back corner of the property where the lateral and back fences meet). We are fine with the aesthetics of the rock corner. I think he has another idea or two besides those.

Also, when I made my previous post, I thought the dry well was literally full of mud. It is not. There are 3-4 inches of mud on the top of it, below the mud is gravel (which makes sense to me).



I am not a landscaper, contractor, or other type of drainage professional, but ISTM that the water’s gotta go somewhere, and the canister “dry well” you describe doesn’t sound like it will work unless it’s really, really big. Even then, presumably it’s got to be emptied at some point.

Is it possible to route a pipe, a few inches under the surface, from that lowest point to the street? Is there anything blocking it (like your house), or would it require excavating more than inches, since it would have to be gently but continuously sloped downwards?

Well (heh), the dry well is connected to the two lengthy offshoots of tubing that are meant to distribute the water over a large area.

We could run it to the street, but the contractor said that would not be ideal because it would have to run alongside and fairly close to the house (which has a basement). His recommendation is to keep the water away from the house and disperse it underground.


Also none of landscaper, contractor, drainage professional, etc. and I am a bit confused.

I had always thought the dry well was where the French drains dumped into? Then slowly releasing the water deeper under the soil.

This French drain is to dissipate from the dry well after it is full itself? Seems like it’s just dumping it into the wet area.

Why not more like a basin at the low point and drain into a dry well at another location?

I am sure there is a reason!

Maybe I am confusing my terminology. And maybe I’m not understanding what is happening.

@DSeid had me thinking for a second that I have it backwards, but after more thought, I don’t think so.

I believe the purpose of the large container - which will soon be sitting under gravel, not soil - is to collect the excess water and then distribute it along two lengths of underground tubing, each of which has several holes (and sits upon gravel). So the rainwater will spread along both 25-foot extensions of tubing.

I believe the tubes are sloped downward away from the container.

Picture a right angle, 25 feet in each direction. The point where the two lines make contact is the corner and the low portion of the yard - and the location of the canister.


That makes some sense, but ISTM that draining to the street will still be more effective. Can a pipe WITHOUT HOLES be routed around the house to the street?

But those lines are connected near the top of the dry well, yes? So sure after the dry well is full they will spread the water out over a larger area … but by the time the dry well is full ISTM that the ground at least anywhere near the dry well is also already saturated.

The rocky corner as a target to dump off to can only work if it is lower itself … or has a second dry well placed there.

Or equally possible (maybe higher odds than that) I am missing something …

How big is the dry well itself? And it IS a perforated container?

How big is the area that usually gets swampy? (Or IOW how far away beyond it do the French drains do?

The contractor will probably expand the area/volume that the drainage perf tubs leach into. More sand and gravel over a wider area, perhaps deeper. The rock corner is an excellent idea.

I guess…do these sort of drains usually have holes?

I don’t know where the connections to the dry well, top, middle, or bottom. But the corner is definitely the low point of the yard. It already pretty much was, and then the contractor sloped the grade in that direction.

The dry well is, I’m guessing, about the size of an oil drum. Actually, probably a bit smaller. Let’s say it’s between an oil drum and a beer keg. Yes, it’s perforated. The size of Mustard Swamp varies a bit, likely 15x15 to 20x20 feet.


If it doesn’t have holes then I’m not sure why it would be dangerous to route near your basement.

Agreed, and this was the solution I originally envisioned before we even started contacting landscapers.

Maybe that will be the final solution if the next efforts fail.


You may find it useful to read this:

and this:

Again, I am speaking as an ignorant person trying to make sense of the set up …

My limited understanding of French drains was that they take water from where it is collecting to dissipate a bit more underground in an area that is not where the water is collecting. The area of the drains’ effluent that is within the footprint of Mustard Swamp accomplishes little I would think, and it sounds like most of it is. That’s where the water already is.

(The dry well OTOH both gives the water a head start deeper underground, and allows the volume of the well to be delivered into the ground more slowly. Between the head start and the slower release it gives more time for the water to drain. It seems like that barrel is too small for the volume of water a storm delivers.)

Those 2 articles are good reading. My understanding of French drains is similar to Dseid’s - tho I’ve heard terms such as French drain and dry well used confusingly/interchangeably. Our downspouts connect to buried flexible pipe, which runs to a lower spot away from the house. At the end of the pipe is what we understand to be a French drain. It is a rectangular box a couple of feet square buried underground. I’m not sure if it is filled with coarse gravel or only surrounded by and on top of it. The bottom is grated, allowing water to soak down into the ground, and there is a pipe going up from the top to the surface of the lawn, out of which overflow runs in the heaviest rains.

I’ve also had experience directing water with top and bottom perforated pipe and swales.

What the OP describes is different from anything I’ve experienced, and I don’t really understand the idea. I would, instead, imagine a couple of cradle filled trenches running away from the low spot. Have you asked the installer to clearly explain why it is constructed that way, ad how it is supposed to work? Because your questions and experiences are just what I’d expect.

One other thing to consider might be the possibility of planting plants that are good at soaking up excess water. Or possibly creating a “rain garden.” Good luck!

Here is the theory: Imagine the back corner of the yard is the problem area, maybe 20’ x 20’. It is also the lowest area of the yard.

The landscaper places a perforated barrel underground, maybe 3-5 feet out from the actual corner. It is nearly full of gravel. Connected to that barrel are two 20-25 foot runs of perforated, underground tubing. The two outflow tubes run parallel to the side fence and the back fence, perhaps 5 feet out from the fence.

The ground is sloped down toward the underground barrel. The plan is for the surface rainwater to be diverted toward that barrel, seep down into it, then out either length of tubing where it will be dispersed underground.

It was obviously not seeping fast enough after the rain the other day, since it pooled on the surface. The landscaper is going to create a rock “garden” in the corner of the yard - at the low spot and above the barrel. When first installed, there was soil - not rocks - between the top of the barrel and the surface. He may also extend one or both of the tubes that run from the barrel.

Have I cleared things up or muddied up the picture even more?


Found this photo online that is close to what I have, except for this container seems to reach the surface of the lawn while mine is underground. Also, I have two runs of tubing coming from the container.