# corrugated drainage pipe, how to couple?



## bubbler (Oct 18, 2010)

My front yard is about 8' higher than my back yard. I've had some basement water issues in the past and I'm currently working out the grading on one side of the house. While I've got it all dug up, I thought this would be a good time to lay down some drainage pipe from the front to the back to allow one half of my front gutters to drain directly into the same line as my sump pump and back gutters.

I wanted to use sch-20 pipe which is what is already used for my sump pump, but HD didn't have what I wanted, only this black stuff with white wrapped around it.

Instead I opted for the inexpensive corrugated pipe (the non-perforated kind). I am covering about 30' of distance, so I needed three 10' lengths, I couldn't fit the 100' into my Honda Civic, and anyway I only needed 30'... 

What I'm finding is that the joints all leak like sieves... but the worst offenders are the 90* elbows. With most of the couplings you can arrange to have the "uphill" pipe connection INSIDE the "downhill" pipe... so it's like the uphill pipe is male, and the downhill is female. 

But with the 90* elbow, BOTH sides of it are female. What this means that at least one side of the elbow ends up with the downhill pipe acting as a male, meaning it fits into the elbow (which is uphill) this is obviously no good, it's like trying to loosely join a 4" pipe to a 3" pipe where 4" is the supply side--all the water will just spill around the space between the two...

Is there something that I'm missing here? How are these 90* elbows supposed to ever work? Unless you have an absolute gusher flowing I would expect that the majority of the water will just end up seeping out around the joint into the surrounding soil.

I've seen some people say that using roof tar (I'm thinking Henry 228 in a caulking tube) will do a good job of sealing the joints... and in deed I will probably do that for the majority, but the 90* elbows just seem incorrectly designed, it seems like they should have one "make" and one "female" end...


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## Ravenworks (Oct 31, 2010)

Go back to the store and buy some bags of cement,I use one bag per fitting,end of problem.


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## Jasoncarpentry (May 28, 2012)

(I'm new to this site, and I hope you folks can help me.)

Bubbler, I don't have an answer to your question, but I do have similar concerns. I need to replace two drainage lines from two downspouts. My site is simple: good slope, and I can "daylight" into several acres of woods behind the house. I just bought three 10' lengths of 4" solid corrugated pipe, two downspout-to-line adapters, several unions, and a tee to join the second downspout to the line. Here are my questions:

1. Like you, it seems to me that, instead of unions, I should simply place the uphill end inside of the start of the next line downhill. This is so obvious to me, I don't even know why they make the unions. I'm about ready to return them to Home Depot.

2. The tee is another story. Like your elbows, I have to use a pre-made fitting, and I worry about leakage. I could use caulk, but it bugs me that I have to go to such lengths to make a $5 part work properly.

3. Nobody seems to agree on what type of trench to use. I'm not worried about freeze protection, since, even in cold climates, a downhill gravity line is self-draining. So I plan to dig a trench of minimal depth. Shoould I line it w/ gravel? If so, what size? I don't see the need to line it w/ ANYTHING, since it's a solid line, not a perforated one.

4. Should I use a "critter guard" where it daylights at the end? If so, what kind?

Since I have a bad back, I'll probably hire this whole job out to a strong friend, but he probably won't have the answers to my questions.

Thanks in advance!

Jim in Tennessee


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## bubbler (Oct 18, 2010)

Jasoncarpentry said:


> 1. Like you, it seems to me that, instead of unions, I should simply place the uphill end inside of the start of the next line downhill. This is so obvious to me, I don't even know why they make the unions. I'm about ready to return them to Home Depot.


This is what I ended up doing, I had to flip around a couple of pipes and change a fitting at the top to a different type (flex hose instead of 90s)



Jasoncarpentry said:


> 2. The tee is another story. Like your elbows, I have to use a pre-made fitting, and I worry about leakage. I could use caulk, but it bugs me that I have to go to such lengths to make a $5 part work properly.


I used Henry 228 roofing cement at my T. I bought it in a caulking tube, it seems to hold fairly well. I also used it at the coupling between my corrugated pipe and some 4" schedule 20 that was already there for one downspout--even though they make a fitting specifically for this union, and it's got the correct uphill->downhill orientation, it still leaked like a sieve... half a tube of roofing cement later and it's not leaking.



Jasoncarpentry said:


> 3. Nobody seems to agree on what type of trench to use. I'm not worried about freeze protection, since, even in cold climates, a downhill gravity line is self-draining. So I plan to dig a trench of minimal depth. Shoould I line it w/ gravel? If so, what size? I don't see the need to line it w/ ANYTHING, since it's a solid line, not a perforated one.


In my case my yard sloped TOWARD my house at the side... so I dug it down a bit further, laid the pipe, now I'm filling it up with whatever dirt, rocks/debris I have handy. Nothing massive, but it is def. the "garbage". I also had a few yards of top soil trucked in that I will lay over it all to create a slope away from the house.



Jasoncarpentry said:


> 4. Should I use a "critter guard" where it daylights at the end? If so, what kind?


My pipe just exits a gentle slope. I bought a 4" sch 20 outer coupler (so it fits OVER the pipe) and an "NDS 4" Green Atrium Grate", which fits perfectly into the end of the coupler. It's not designed to be used horizontally, but I decided to with it because it looks better than a 4" pipe hole, and will keep animals from nesting in there during the dry spells.


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## Ravenworks (Oct 31, 2010)

> I used Henry 228 roofing cement at my T. I bought it in a caulking tube, it seems to hold fairly wel


I assure you that it is *leaking* by now,when you fix it take my advice from the post above.
What you did may seem to work for you but it didn't and was a waste of time.
The system is designed to leak which helps promote the picking up of ground water.
To do the job right you should never use the black pipe around your house except for a weep system.
You need to use hard pipe and glue the fittings all the way to the end,they also make hard pipe for weeping as well.

As for your back fill, there should be *NO rocks or garbage* in your ditch within the first 6" of fill.


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## bubbler (Oct 18, 2010)

Ravenworks said:


> I assure you that it is *leaking* by now,when you fix it take my advice from the post above.
> What you did may seem to work for you but it didn't and was a waste of time.
> The system is designed to leak which helps promote the picking up of ground water.
> To do the job right you should never use the black pipe around your house except for a weep system.
> ...


I've got a fairly good slope--about 8' over 30' and the water being carried is from a downspout. The connection from sump pump occurs at the bottom corner of the house, in a worst case situation some percentage of the water being pumped out maybe find it's way out of the pipes, down the soil, and back into the pit, but based on what I saw from running a hose for 20 mins (nothing) I'm not that concerned. 

The roofing cement job was done about 4' "downhill" from the end of the house where the two pipes meet (black and sch20), there is good slope there, with no roofing cement I was getting just a bit of dribble with the hose running, with the roofing cement it was stopped. I appreciate the idea of using a bag of cement to encapsulate the union, but it seems like overkill as long as 80-90% of the water continues down hill in the sch20 pipe.

If I had this to do over again, I would have kept the entire setup sch20, but unfortunately I didn't have it available at HD or Lowes, and the local lumber yard keeps bankers hours.

As for fill, when I say "rocks", I'm talking golf and fist sized or smaller, not basketball. And by "garbage" i mean that I'm filling it with the dug up mulch from last year's beds, and other assorted dirt from around the yard, not literal garbage. I know that filling like this will lead to more settling than usual, but I'm prepared to live with that. It provides me a way to get rid of the extra material, and also keeps my costs lower because I'm not trucking in load of additional material just to cover up a pipe. This pipe is also running along the foundation, it's a zero traffic area so being crushed is not a concern.

In a worst case situation the black pipe setup will fail within a year or two. I will have lost the ~$50 I spent on pipe & fittings, plus my hours of labor, and I will replace it with sch20. This year I just needed to get something done.


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