I’m not sure it goes to the storm sewer.
I’m not a plumbing guy. (Nor an electrical guy, nor any other household systems guy. They’re like my smartphone – I know how to use them, but not how they actually work.) That pipe is right above the sump pump. Could it be some kind of vent? But then, why would there be drain pipe emptying into it?
Can someone volunteer a clue for me?
Do you mean a combined sewer and stormwater pipe? Usually not okay to hook up stormwater with sewer water. Is there a separate collection system for gray water/ stormwater?
See, that’s what I’m talking about. I don’t have a clue!
It might connect to the public system, or it might just be a french drain or a dead end.
Can you see the bottom or tell how deep it is? If it ends in gravel, it’s no help. If it connects to a horizontal pipe or has an elbow at the bottom, maybe it leads to the public system.
You can get a “cheap” drain camera like this to see where it leads, or maybe your public works or building department would have records if it was permitted. Companies like the ones PackerMan2 mentioned would know the best way to figure it out, and they could probably give you advice as part of the quote process before you even hire them.
Side note: different places handle water like this differently. Some, as chela says, don’t allow stormwater discharge to the sanitary sewer. Others don’t allow connections to the storm system, or they have a single combined storm/sanitary system.
The other day, I dropped a pebble down it. (The scientific method 
) It sounded like it hit PVC, so yeah, probably an elbow. But I’ll need a pro to tell me where it leads and how (or if) I can use it.
Did you say the downspout has a patio on one side and a driveway on the other? Hopefully these are sloped away from your house. If so, all you need to do is get the water to one of those surfaces - via an extender, from which it will drain away downslope.
Both the patio and driveway slope away from the house … eventually. Problem is, extending the downspout to where those slopes begin would make it a tripping hazard on the patio and risks it getting run over on the driveway.
The seam between the patio and the driveway – where the current fence stands – is a gathering point. It’s clear of the foundation but has wrecked the fence.
Sorry - couldn’t really tell from the description/photo.
I’m also in N IL, and see every conceivable arrangement of downspouts/extenders/French drains/etc. I imagined an aluminum or flexible extender could run under the left part of the fence, past the trash cans to the edge of the driveway, or could directed back behind the fence to the unseen patio. Optimally, both surfaces should be pitched away from the house/garage. Tripping/driving hazards were not clear to me. If it discharged on the driveway next to the trash cans, it would not flow away?
I’m still wondering if some sort of extender could be run along the side of the house, behind the trash cans, to a point where it could empty onto the edge of the driveway downslope - where it would be less at risk of being run over. I should mention, tho, that nearly every aluminum extension I see shows signs of having been stepped on, run over, etc! 
And I’ve never tried/seen one of the roll-up/flip down extenders that worked reliably over time.
What you say about the house being L-shaped, such that the gutter can’t be reversed, makes it clear to me that I have no idea how your house/driveway/garage/patio are situated. Apologies. I’m sure you are trying to be very clear. Just observing how this one reader see it.
Yeah - check with your municipality as to whether the storm/waste sewers are separate, and what they allow in terms of hooking up downspouts. Our city (Elmhurst) has had major drainage issues, so such things are spelled out clearly. If that grey water/sup/ejector discharge is nt connected to a sewer, I would expect that you would be able to locate a surface level discharge.
To the left of the cans is where the L of the house juts out, forming a rectangular paved area big enough to park a small car. No way I want water draining into that.
If I ran the extender just a few feet out from the house (perpendicular to the wall with the garbage cans) water would probably drain across the driveway. But it might also back up into the seam between the patio and the driveway, and/or form a sheet of ice on the area of the driveway directly outside the gate. My dog and I would need skates.
I truly appreciate your (and everyone else’s) efforts to understand and help me solve this problem!
Prior to this house, we lived in 2 where the ground was poorly pitched, and getting water away from the foundation was an ongoing issue. So I feel your pain.
Here’s another idea. Can the downspout be redirected along the wall at a descending angle, around the “L”/parking space? Or, as someone mentioned, switch the pitch/sownspout to the inside corner of the “L”, and tweak the downspout to take it along that side of the “L” to the driveway?
Might be worth your while to spent a little time on your driveway with a hose to see exactly where the pitch away from your house begins. You should KNOW where the water would pool, rather than being unsure if it would flow back to that seam.
Good luck! Some folk undoubtedly woulda thought we were foolish. But when we bought our current home, one of the most important factors was that it sits up just slightly higher than its neighbors, and slopes down to the from and back yards - allowing us basically free rein in redirecting water.
Our nearest neighbor’s house is close to the far end of our barn. They recently built another outbuilding on their property as a woodworking shop, which necessitated cutting down several mature trees. Loss of the trees and the runoff from the new building led to their yard in front of the new building becoming swampy.
They asked if we’d be ok with them diverting the water from their property over to our property, where a French drain exists by our barn. Wanting to be neighborly, we agreed. Neighbor dug a ditch ~40 yards by hand, laid pipe & gravel, etc, reaching our French drain.
Turns out the volume of water overwhelmed our French drain and created problems on our property. Our neighbors were mortified and promised to fix the problem. Before they could, we planted three curly willow trees that are thriving, and the problem is 90% improved.
Lateral and subjacent support - terms anyone w/ 1 year of law school remembers!
Folk so often seem clueless about the amount of water trees soak up. In our old neighborhood, on a cross street behind us was a triple wide yard, much of which was wooded. Mostly trash trees/ brush, but at leas a few sizable oaks, maples, etc. Some millionaire bought that entire part of the block, tore down one house, clear cut it all, and threw up a mansion. Replaced all of that greenery with a few strategically placed ornamental seedlings. Lo and behold - all of the folk whose property backed up to that property began having major water problems, when thay had had none for the previous decades. I’m SURE it was just a coincidence… 
Fraid not. The roof section with that gutter ends a few feet to the left in the pic, and the rest of the wall going forward toward the L is two stories high.
The downspout is in the only place it can be. The only question is where to direct the outflow.
I’m afraid I’m unclear. Let me see if I can explain.
The wall the downspout comes down is a rectangle (considering the portion below the gutter - to the corner of the L). Right now the downspout goes down the right side of that rectangle as you face it. With a couple of angle joints, you could have the downspout turned to the left and follow the wall down at an angle - basically splitting the rectangle into two equal triangles? Got it?
Now you don’t want that, because it would dump the water at the inside corner of the L. And there might be windows in the way, so you don’t want to start the angle way up at the top. But you MIGHT be able to be creative (or HIRE someone to be creative), such that the downspout flows straight down for a bit, then turns to the left such that it runs down at an angle to the corner of the L, and then angles onto the wall that is the other side of the L, where it continues on a downward slant such that it discharges somewhere at the end of that other wall - where hopefully the driveway flows away.
This video shows how to cobble together elbows to go around the OUTSIDE of a corner. Perhaps you could do the opposite to go around the INSIDE of the L-corner.
Let’s see if this does anything other than confuse things:
|
| Here it bends to left to angle along the wall
/
/
_ _ /
/ Here a series of elbows takes it around the inside of the L
/
/ Here it continues to angle down the wall on the other side of the L
/
/ Discharge onto driveway
We’ll see how that comes out. I’m sure it will confuse things more than anything!
Would end up with a long run of downspout along the side of your house with several angles. But if done professionally, it should be solid and shouldn’t look too bad. And would get the water where you want it.
I truly appreciate how much effort you’re taking to help me solve this problem, and your graphic has me laughing.
What I’m failing to convey is the distance involved. Let me see if I can apply your method:
---------- current gutter
|
| current downspout
|
| proposed relocated downspout
/
/
/
-------------------------- long wall to L
/
/
/
---------- short wall after L
/ water exits
In short, it’s a long way that would require a lot of downspout and precise engineering. Probably not impossible but almost definitely ugly.
I hesitate to mention it because routing downspouts across walls is unattractive, but what about the other direction? Instead of turning left toward the driveway, what about right and wrapping around the back of the house? Is there a clear enough shot that you could get past the patio and discharge to the back yard?
If I couldn’t be useful, I’m glad I was entertaining!
When we walk the dog, and when I bike, I see just about every possible permutation of downspouts - INCLUDING one like someone jokingly mentioned, with a flyover from the house to the garage. To think that in another thread, folk expressed surprise that passersby would notice whether curtains are open or closed. Hey, we look at and discuss gutters, concrete work, gas meters - basically anything visible on homes as we pass.
Good luck. And keep laughing!
Nope – that’s where the back door is!
Now I’m imagining a veritable Habitrail of downspout along that wall, complete with a loop-de-loop.
OK, so change the back door so it opens inward, get one of those “low clearance” signs from the hardware store…
UPDATE!
My fence guy insists that properly anchored fence posts won’t be so easily displaced by underground ice. Also, since I’m replacing some blacktop with gravel to accommodate the new, rectangular enclosure, the larger drainage area should make run-off less likely to pool and freeze.
Long story short – I’m not making any changes to the downspout.
I’ll post pics once the work is done. Thanks again to everyone for the wisdom, the suggestions and the laughs!