View Full Version : How to divert water from downspout to street.

Bill Jobe
05-10-2018, 11:19 AM
I have a drainage problem at one corner of an attached garage. I installed an oversize downspout, but I need some way to divert that water as far away as possible, preferably to the street about 35-40 feet away.
I'm thinking of going with an adapter to attach 4" flex pipe and run it down the edge of the driveway to the street. There should be enough drop to make it run, that is, if I don't bury it.
I don't mind too much with it showing. Hopefully this will be a temporary fix until I figure out how to build the ground up after the slab is poured at the rear corner of the garage. I intend to bring in some dirt and raise that whole area up higher than the surrounding terrain. I have a serious problem there, causing the foundation and garage floor to sink.
I do not as yet have a plan as to how to address the damage, but in the mean time I must keep that area dry.

Does anyone have a better idea than this? I don't really want to bury anything because street level just will not accommodate it. This must work regardless of how it looks and I have the additional problem of one of my wife's favorite flower beds on that corner and do not want to cause discord with her.

Bill Jobe
05-10-2018, 11:34 AM
Would drain/sewer pipe be better that the flex, spiral pipe? I think a 3" would handle about as much water as a 4" flex pipe.

Bill Dufour
05-10-2018, 12:45 PM
At my house I buried the flex drain pipe and I cut the concrete curb so the pipe bottom is at the level of the apron.
Bill D

Bill Jobe
05-10-2018, 1:00 PM
At my house I buried the flex drain pipe and I cut the concrete curb so the pipe bottom is at the level of the apron.
Bill D

Thank would work great in my situation.
But I'm not sure about the codes.
I'll look into that.

John C Cox
05-10-2018, 2:04 PM
That flex stuff kinda works - but it's quite fragile and it does not flow anywhere near the volume of water of a smooth pipe.... So for example - the area of that cheap black 4" flex "drain pipe" is almost double that of a 3" pipe, but it only flows about half the water... The stuff tends to crush ridiculously easy - and simply stepping on it will crush it.... It also clogs ridiculously easily but is very difficult to unclog because of all the ribbing. For example - leaves and pine needles will drive you to distraction.

If you can swing it... Use 3" or 4" PVC DWV pipe and couplings. I wouldn't even bother to glue it... Paint it green to match the grass or grey to match the cement... Just connect it with the flex downspout adapter and off you go...

but if your main concern is cheapest and fastest solution - go with a roll of that black flex stuff and just throw it away if you ruin it...

W Craig Wilson
05-10-2018, 3:11 PM
I'm thinking... run it down the edge of the driveway to the street.
Do a quick check with your local building authority. Many municipalities do NOT allow such flow to the street. Such excess volume can overwhelm the storm sewage system.

Wayne Lomman
05-10-2018, 4:02 PM
A smooth bore pipe will be better. You should be okay with the local council if you tell them it is temporary while you do the permanent solution. You are entitled to take steps to protect your house from serious damage. Cheers

John K Jordan
05-10-2018, 5:01 PM
Do a quick check with your local building authority. Many municipalities do NOT allow such flow to the street. Such excess volume can overwhelm the storm sewage system.

If there is no way to drain it you might consider a dry well to disperse water underground. There are many types - the simplest is to dig a big hole and fill with gravel. Run the drain into the hole. Google dry well for more information. Also see if it is allowed on your property. No problem on a farm. Check for underground utilities before digging!

How well it will work depends somewhat on the volume of water, the size of the dry well, and the type of soil and how well the it percolates. People who put in septic systems can test the soil.

You can also run a long length of slotted drain pipe, the type used in a french drain. Dig a wide trench, put gravel on the bottom, lay down one or two runs of flexible slotted drain pipe, cover with gravel, then put soil on top. It is sometime desirable or required to wrap the pipe and gravel with geotextile cloth to keep the soil fines from saturating the gravel.

You can temporarily lay a long length of the slotted drain pipe on top of the ground and see how well the soil in your yard absorbs the rain water from the downspout. I do this behind my shop, with the pipe on top of the ground, downhill into undergrowth.

Bill Jobe
05-10-2018, 6:45 PM
It's done in front. Took me about an hour using 4" drainage pipe and fittings for 90s and adapt to downspout.
My wife told me I can't run it to the street so I took 10' off. The driveway slopes enough for it to make it to the street.
If the city doesn't like it I'll figure out something else.
The inspector knows why I ran it that way. It rains for a couple of days now and my contractor hopes to do the excavation at least, first part of the week.
It's just a temporary fix til I get my shop.
They are death on sump pumps diverted to the street, but I think they will be OK with my temp setup.
I chose to not run the back downspout to the street and instead will run it as far away from the excavation area as I can. When it's all done I'll make something permanent.

Ole Anderson
05-11-2018, 8:40 AM
And when you regrade, be sure not to spill water on your neighbor that he is not already receiving.

John C Cox
05-11-2018, 8:50 AM
If you run into trouble with too much water everywhere and mushy mess during the work.... Or making a lake in your lawn. Consider using a golf course soil wetting agent. They make water soak into the soil super fast. Typically - 1 application lasts 3-6 months. Golf courses use them because nobody wants to play golf in a mushy squishy slushy mess.... So they need the water to soak into the soil instantly.

The brand I am familar with is "Cascade plus". NOT the dish soap! You buy it at a turfgrass or golf course supply store. I had some drainage/runoff/erosion issues because of living on a hill and ended up just putting that stuff down.. And HOLY COW. Water would run down the road /swale from the neighbors houses and go about 6' onto my property - and the ground just slurped it all up... It was weird to watch a 3" deep flow of water simply disappear.... The erosion issues completely disappeared because all the water soaked in - nothing ran off..

Bill Jobe
05-11-2018, 10:39 AM
And when you regrade, be sure not to spill water on your neighbor that he is not already receiving.

Yeah, gotta be careful about that.....she's the town bully.

Bill Jobe
05-11-2018, 10:55 AM
Got it all buttoned up in back now with 4" solid drain pipe running 15' or so to the rear of the excavation area. I also covered the entire thing with 6 mil plastic. Hopefully it'll be dry as a bone if and when the crew shows up.
As much trouble as I've had getting anyone out here I'm not holding my breath.
My shop is built and waiting.
Construction I my area is crazy. Not enough companies to keep up. Many have waited as long as I have.

Bill Jobe
05-11-2018, 11:04 AM
Sure glad you guys steered me away from the flex pipe and to solid drainage pipe. So very easy and fast to use. And with carefully sloping it, no buildup with water to cause backup. And very little in the way of fittings! I like that. The terrain was perfect front and back for drain pipe.

And I've been thinking about taking the dry well advice,too. Too bad I sold my 275gal poly tank a couple of years ago. That would have worked pretty good.

Perry Hilbert Jr
05-11-2018, 11:38 AM
The city fathers and even your neighbors may not like the idea. I did that exact same thing when I lived in another state. I ran the drain under ground and out through a hole I cut in the curb. Once in a while there was a problem with the drain water freezing on the road in front of my house. Sold the house and moved out of that state. Apparently 6 yrs later, according to a friend that still lived across the street, the city knocked on the new owner's door and handed him a letter to change the drain and they tore up the curb and fixed the curb. Sent the buyer the bill for curb repair. The adjoining owner had done some regrading and the drainage problem became even worse with water in the basement for the first time. There is a house in the neighborhood that runs a sump pump drain out onto the street. There is always some water flowing. it freezes in winter and it is just a matter of time until the guy gets sued.

In the US, some states have exactly opposite rules about what you can do with storm water and run off. You state or municipality may have some seemingly irrational rules concerning riparian rights. Some places you can't block or redirect the flow, other places you can do what you want, so long as you don't cause damage to a neighbor.

John C Cox
05-11-2018, 2:30 PM
So true.

Last town I lived in was fairly hilly... And the town didn't have any useful sort of storm water planning for most businesses... So everybody's storm water gushed straight down out of the parking lots onto the main road... And it frequently flooded the road and caused all sorts of accidents from cars hydroplaning....

Move here and the business properties can't have any "outfalls" onto city storm drainage... They have to have their own retention ponds and dry wells to catch all that stuff and let it soak into the ground...

I certainly don't miss watching a foot of water roll down out of car lots into the main road and down the middle of the state highway....

And so it goes.

Bill Dufour
05-13-2018, 12:37 AM
If you live in the western states Spanish water laws are strictly enforced. You do not own rights to the water on you land unless no one downstream has ever used that runoff. That runoff recharges groundwater downstream so you have very little rights if anyone downhill has ever had a well or pond.
The OP did not say where he lives. I would expect the water rules to be strict in Africa, Mexico and Australasia
as well as the Western US.
Bill D

Bill Jobe
05-13-2018, 3:29 PM
No, Midwest here. We don't have water wars like out west. They truly have a serious problem that ain't going to get much better.
Very few problems where I live. At least for the time being. But water is going to be a precious commodity it the near future. We are driving it into extinction.
I recently read a report on Lake Mead, I think it was. It is disappearing.

Bill Jobe
05-13-2018, 3:31 PM
Rains here again tonight. So far no one has said anything to me about my temporary setup.

Bill Dufour
05-13-2018, 10:00 PM
The problem with lake mead is that different water agencies have each been promised a certain amount of river flow each year based on historical water flows. Problem is the research did not go back far enough and the actual flow averages less then the total of the promised amounts. Since 1936 Las Vegas and Arizona have expanded and are wanting their full allotment so there is not enough to go around anymore at the promised quanities.
Bill D

Rod Sheridan
05-15-2018, 8:24 AM
Do a quick check with your local building authority. Many municipalities do NOT allow such flow to the street. Such excess volume can overwhelm the storm sewage system.

Where I live there's a legal requirement for "downspout diversion", which means I had to disconnect all the downspout I could from the storm sewer connection.

All the downspouts on my house were disconnected except for the one at the front where it's only 1 metre from the sidewalk, so a variance was issued by the city for that one.....Rod.