Sizing the main pipe depends on a number of factors, but the primary one is how high can the water back up without the 'leakage' becoming too much? If you have at least a foot or so of drop between the drain inlets and the outlet, but it's not sealed at the connection between the downspouts and the drain pipesit can back up and overflow excessively where the downspout connects to the drain, you'll need a drain line with a cross-sectional area at least as big as the combined cross-sectional area of the downspouts flowing into it.
So, if you have four 3"x4" downspouts, the line out to the street would need to have and area of 3*4*4 = 48 sq in., which is 7.8" diameter ----> d = square root of 4*Area / Pi (4*48/3.1416)^.5 = 7.82".

If the downspouts are at sealed to the drain lines so water can back up into the downspouts without spraying all over, I estimate you could drop to about 60% of that area (6" pipe).

 

We have big house with big roof and all the downspouts leave the property jointed to the perimeter drain from the foundation in a 4" pipe.

 

What type of drain pipe should I get?

4" convoluted drain pipe at every BBS! No clean out required, install gutter foam to keep the crud out!

 

Depending on how much rain you get at any one time and how big your roof area is, since you have to dig a trench anyway it would go with 6". My vote would be for hard pipe over corrugated 'flex pipe'. A little more complicated to install and more expensive, but no matter how hard you try, dirt and crap from the roof will accompany the water and the rough surface of the flex pipe will tend to trap debris and, over time, can impair flow. Clean-outs I guess would be nice but I think with enough slope to ensure good flow, and a straight run you should be fine. In all of our homes, I don't think I've ever had one clog. We've always lived in the country - autumn leaves and all - so always run to daylight.

 

Thanks. What I am concerned about if you look at my picture is the 90 degree turns going down the side of my house. I heard that they are not good for Drainage and I should use a "Y" fitting instead of a "T" fitting, thoughts on that?

Also the drain should ideally drain out of my curb which means core drilling through my curb, wondering if I'll have 6 inches to spare there. I need to measure my curb.

Thanks

 

What would the alternatives be? If they say I can't do that?

Drain to the creek in your backyard!

And don't overthink this, 4" convolute is fine, I've had it in the past 5 homes, current house is going on 17 years, corners just give a nice radii. 6" pipe is more expensive and not as readily available.

Slope is the answer, you need good/great slope then anything that does get in the pipe simply flows out. If it's flat, that is when you get clogging issues!

Got to use guards on the gutters to keep debri out, another lengthy discussion.

And no matter what size you install there will always be that one rain every now and then that overwhelms the pipe, it's happening now without the pipe, it just happens!

 

What would the alternatives be? If they say I can't do that?

Drain to the creek in your back yard!

No creek, my yard slopes to the curb.

 

Thanks. What I am concerned about if you look at my picture is the 90 degree turns going down the side of my house. I heard that they are not good for Drainage and I should use a "Y" fitting instead of a "T" fitting, thoughts on that?

Also the drain should ideally drain out of my curb which means core drilling through my curb, wondering if I'll have 6 inches to spare there. I need to measure my curb.

Thanks

If you go with hard pipe, you could use two 45* elbows to smooth out the bend or a wye and just cap the first one. If you go with flex pipe, my other concern is the pieces only snap together and if you have really light soil, it could wash through the joints. When I did run for our daughter's garage, in sand, I wrapped the joints in some landscape cloth.

Are there filters or something to install in the end of the pipe to keep things from clogging up the pipe?

Do you mean the outlet end? Since it's a ground level and the outlet, it shouldn't clog. If you want to keep critters out of it, you can get end caps for many sizes.

My concern with using too fine a mesh is it can cause more problems than it can solve. I had a small piece of 1/2" steel mesh and bent it over and held it in place with a gear clamp.

If you mean at the top of the downspout, I find they just narrow down the location where an overflow will occur.

 

If you go with hard pipe, you could use two 45* elbows to smooth out the bend or a wye and just cap the first one. If you go with flex pipe, my other concern is the pieces only snap together and if you have really light soil, it could wash through the joints. When I did run for our daughter's garage, in sand, I wrapped the joints in some landscape cloth.


Do you mean the outlet end? Since it's a ground level and the outlet, it shouldn't clog. If you want to keep critters out of it, you can get end caps for many sizes.

View attachment 798273
My concern with using too fine a mesh is it can cause more problems than it can solve. I had a small piece of 1/2" steel mesh and bent it over and held it in place with a gear clamp.

If you mean at the top of the downspout, I find they just narrow down the location where an overflow will occur.

Awesome Thanks, this is coming together.

For each downspout pvc line going into the main 6 inch stack, should I use 2 or 3 inch pvc? I am guessing 2in pvc but I want to make sure.

Thanks

 

Also the drain should ideally drain out of my curb which means core drilling through my curb

Check with your city, curbs mean you have some regulations to follow. Most places frown upon cutting their curb. Also, these days most places are wiser about runoff and enforce your discharge to be back on your property at least 3'.

What type of drain pipe should I get?
should I use 2 or 3 inch pvc? I am guessing 2in pvc but I want to make sure
More specifically sizing the main drain for 4 downspouts how wide should the drain pipe be?
should use a "Y" fitting instead of a "T" fitting, thoughts on that?
Should I install a cleanout on each downspout?

Save yourself future trouble, do it right the first time, and skip the black corrugated. The only 2 positives are it's cheap and easier to install (and the ease is what causes some of the problems), but for some reason people avoid all kinds of products with those 2 qualities everywhere else in their house, cars, and bodies except don't apply the same experience to storm piping.

Use rigid, solid Sewer&Drain PVC, HDPE, or poly pipe. All underground storm piping must be 4" per code. That will hold a lot of water + air, and your downspouts are never full either, so 4" everywhere is perfectly adequate. Use Sewer&Drains fittings - wyes to turn from a branch to the main line, adapter at downpout. You only need 1 cleanout at the high end of the main line, in case something furrows in it. Otherwise, using rigid pipe, with slope, means debris will wash out (or to the end of pipe with a pop-up emitter). You don't need cleanouts at the downspout, just remove the downspout if for some reason debris isn't washing out, but you shouldn't ever need to rod it there.

Should I install a drain box/catch basin at the end of the drain?
Are there filters or something to install in the end of the pipe to keep things from clogging up the pipe?

For what purpose does a catch basin serve here? Why would you install a filter on the end to hold debris inside the pipe?

How far down should I dig? I have heard 8 to 10 inches?

You set the downspout adapter (the bottom of 2x3/3x4 transition to a rectangle) right at grade. You set your discharge height. Connect point A to B. If you don't have slope, you have to rework your discharge elevation. Note the pipe can be perfectly level, and if the discharge point is lower, water will drain. But for longer lengths and debris removal, you want some slope, 1/8"/ft min to carry debris.

You can reduce the effective length of your total run (thus reducing the elevation change calculating slope) if you hug the house with your main line and/or angle it a bit as needed.

 

and skip the black corrugated. The only 2 positives are it's cheap and easier to install

That's probably why millions of users use it but sure, expensive and hard is always an option!

After wrestling with all that hard pipe, gluing joints, fighting just getting it all laid in the ditches, get back and let us know how much improvement your seeing!

 

No need to be rude, and 3onthetree is correct - corrugated pipe will not work well for this situation. It may work well in some instances, but not here.

Using sewer pipe here (I recommend avoiding PVC where exposed to sunlight) is, IMO, the better option, and while it is relatively more difficult and expensive than corrugated, it's still fairly easy and inexpensive.

 

With rigid pvc do you still need to wrap it and surround it with Drainage rock?

Only if it's a leach line. IOW, only if it's perforated and meant to drain water into the surrounding soil.

Also is this good pipe for the project?

PVC, especially white PVC, is very susceptible to degradation from UV light. It will become brittle after a year or two in the sun.

 

As Rod said, you are not dumping (leach pipe) into or collecting (french drain) water from under the ground, so no fabric or rock as your pipe is 100% closed solid. You are transporting water from point A to B. The UV resistance shouldn't be a big deal if it's all underground.

 

Thanks , I imagine the only part of the pvc pipe if any that would be exposed would be the part that connects the downspout to the pvc pipe. I assume if we could connect the downspout just below the soil line we could avoid this UV issue.

 

PVC, especially white PVC, is very susceptible to degradation from UV light. It will become brittle after a year or two in the sun.

Maybe that is why the standard is pretty much corrugated black pipe. I can not believe all the crap being spread on this post about the use of this material for a simple drain usage!

 

I can't believe you're getting so uptight about people's remarks about a style of pipe.

 

There is no issue with UV degradation. All pipe is underground. The only exposed portion should be the rectangle 2x3/3x4 top of the downspout adapter. You do not have to worry about it getting brittle, no one is driving over it, it is not pressurized, it is air gapped around the downspout. And black corrugated is not the standard, it is just the choice used by people who are only concerned with cheap and easy, just like they chose orangeburg at one time.

 

you're getting so uptight

No, just the typ **** that people spread about common products that are used again, again, again, again to fix issues.

Hey, lets start a discussion on why we should not use nails in construction, that would be even more entertaining!

 

No, just the typ **** that people spread about common products that are used again, again, again, again to fix issues.

Wow, you really do love that corrugated black pipe! Either that or you just thrive on arguing for its own sake.

 

Wow, you really do love that corrugated black pipe!

Probably just as much as the millions of homeowners and professionals who install the same every year! Yet your contradicting an industry standard material as being inferior!

 

Yet your contradicting an industry standard material!

I'm not contradicting anything. I'm just saying it's not the only option, and IMO it's not the best option for some situations, including the OP's. Just because it's popular doesn't make it the best. Its popularity is due primarily to it being the cheaper option, not its functionality or durability.

 

being the cheaper option, not its functionality or durability.

Your on your own with that opinion!

 

I don't think so. Look back at the responses in this thread. I think I'm in good company.

 

Guess it all depends who you ask!

 

Guess it all depends who you ask!

I suppose it does. I asked my brain, and it told me that a smooth wall pipe will be less prone to getting clogged with debris.

 

It's ironic that the googled quip on freezing water directly goes against using corrugated pipe.

It's the internet, and anyone is free to offer any advice they want, ultimately an OP can choose what they want from the information they get. The important key in this is that someone is equipped to understand how to discern between information, or know that there might be a history of industries, teams, or individuals who know a thing about something they don't, and try to learn more about it (whether OP or commenters).

Popularity is kind of finicky. It's popular to still call it "cinder" block. It's popular to put drywall in shower surrounds. Home Depot still sells flexible sink drains because it's popular to buy them.

 

Hi All,

I am reviving this thread. I am having a new pool installed in my house and my engineer deemed it necessary to put drains around one side of my pool because I have a negative grade slope in my yard going towards the pool. Anywho, as luck would have it he has the draining out to the front yard. I asked him if he could include me tying in my downspouts into the main line which he did.

So now I have drawings (which were approved by my local town) to install a several 6in circle drains around 1 side of my pool, tying in all 4 of my downspouts and running it down the side of my home into my front yard all using 6 in pipe. He didn't care what type of pipe I used and have the pipe end with a popup emitter somewhere in my front yard.

I am going to have the pool crew help me dig a little so it shouldn't be an issue but I need to know what I need to buy.

Downspout Adapter and wye cleanout material. This connects to 4in pipe so I need to connect this to the 6in main pipe from each downspout:

NDS HIPS Offset Downspout Adapter, 2X3 in. Downspout X 4 in. S&D Hub 904 - The Home Depot

Use this cost-effective and durable NDS Styrene Offset Down Spout Adapter with sewer and drain pipe. Compatible with PVC pipes.

www.homedepot.com

NDS PVC S&D Cleanout Plug, 4 in. MPT 41P8 - The Home Depot

Choose this NDS PVC MPT Clean Out Plug Solvent Weld Fitting in White to close off the end of a sewer and drain pipe. Resistant to corrosion.

www.homedepot.com

NDS PVC S&D 45° Wye, 4 in. Hub X Hub X Hub 4P08 - The Home Depot

Bring in a branch line of a non-pressurized drainage and sewer piping system with this NDS PVC Hub x Hub x Hub Wye. Suitable for use with drain pipe.

www.homedepot.com

NDS PVC S&D Female Cleanout Adapter, 4 in. Hub X FPT 4P11 - The Home Depot

Find the NDS 4 in. PVC Hub x FPT Adapter 4P11, maximum working pressure of 5 psi features solvent-weld connection at The Home Depot

www.homedepot.com

For the drain grates I was looking into this:

NDS 6 in. Plastic Round Drainage Grate in Green 50 - The Home Depot

Acquire the NDS 6 in. Structural Foam Polyolefin Grate 50, green grate's added ultraviolet inhibitors prevent fading and cracking from exposure to the sun at The Home Depot

www.homedepot.com

For the piping I was considering SDR35 pipe vs ADS Solid or perforated pipe. I am concerned with the ADS especially perforated that the holes will inevitably get clogged and you have to backfill with rock and wrap the pipe. I just feel this is more work but maybe I am missing the pros of this pipe over SDR pipe.

For the popup emitter and Catch basin. I thought about using something like this:

6" NDS Pop-Up Emitter with Single Outlet Spee-D Basin (Green) (Each)

NDS Pop Up Emitter 6"

drainageproducts.us

This only connects to 3in and 4in pipes so I need to figure out how to connect the 6in pipe or find something else.

As always you guys are super helpful so I hope I can get some advice and heads up on this one.

Thanks

 

**** My interpretation of "several" means say 5-9, "few" would mean say 2-4, "couple" would mean 2 maybe 3.

Not enough info to understand how your layout is proposed. But that's a lot of surface drains, I can tell you even 30 car parking lots don't have several catch basins. Is your "engineer" a civil for this pool? Also, you don't have to run 6" pipe everywhere, just when several combine (even if that). And you'll find it harder to find all the 6" S&D fittings you want, some combinations say with wyes will be DWV pipe and expensive.

The surface drains running parallel to the pool should have a swale (a portion of grade sloped down from pool). The drains should be at the "vee" of the swale. You mention perforated pipe, the only reason you need that is if you need a french drain. Which, if you really needed several surface drains, you are in a swamp and should have french drains. The french drain should be at the "vee" as well, but you don't want any surface drains upstream of the french drain. So more understanding of what you are trying to accomplish in your backyard. Pictures and slopes would help.

If you only have 4 downspouts, on opposite sides of the house, it may be better to run those sides separately and combine closer to the discharge point. Also, if in fact you had enough water for several surface drains, combined with 4 downspouts, a single discharge is going to want a daylight discharge on top of grade and some erosion control (instead of a pop up emitter on an elbow). But I don't think this is the case.

You have lots of choices for parts and ultimately how you lay this out, but sticking with Home Depot:

- Surface drains should always have a catch basin to collect debris. NDS-6-in-Plastic-Round-Speed-D, or NDS-6-in-Spee-D-Double-Outlet-Drainage-Catch-Basin, or NDS-9-in-x-9-in-Plastic-Square-Drainage-Catch-Basin. If you are connecting to 6" pipe, you'll need an adapter and can only use the square catch basins NDS-6-in-Styrene-Universal-Catch-Basin-Locking-Outlet-1266.

- Any change from 4" pipe to 6" requires a reducer NDS-PVC-S-D-Increaser-Reducer-Coupling-4-in-Hub-X-6-in-Hub. You'll also need a full suite of S&D fittings of elbows, 90d/long turn/45d/22.5d/etc like here S-D-90-Degree-Elbow.

- If you go with a pop up emitter on a 6" pipe, 4" is what is used in residential so you'll have difficulty sourcing 6", but here's the ndspro emitter-for-6-in-round.

- And again, you really don't need a cleanout at the downpout. The wye is huge, sticks up, and looks terrible. If you slope the pipes adequately, there will be little debris collection in smooth rigid pipe. If you need to rod, you can remove the downspout, keep the downspout adapter unglued, and you can rod right there.

 

I attached the drawing that shows this info (should have done this in my last post). Anyhow. There are 3 inlets around my pool only one popup emitter at the front of my yard.

You mentioned a swale and yes my engineer also mentioned this as well.

 

Could have 20 spouts from 1000 sq ft wouldn't matter. More or better would help with lb and longer runs.
Length of run is a factor. I have even used 2 pipes for much of a run vs 1 big one.