I run into many downspouts (and condensate) that terminate into hidden connections (underground pipes) and in all cases I simply write into my reports that all non sanitary sewer water must drain to daylight and if the outlet cannot be found that its location should be disclosed by the seller or corrective action will be needed.
Do you realize what you just said. Passes through the gutter? humm… Radon system wont work too well full of water. 
Does it rain all the time there?
Only when I wash the car :twisted:
That would be a $400,000 home here.
Back in the early days gutters drained to the interior directly to the storm drain. Now everybody uses the old stand pipe to discharge the washing machine. I never comment on what’s right and wrong for drainage. Plumbing code inspector told me that sewer and storm water in certain parts of the city combine together. I guess that would explain sewage coming up out of the storm drains during a flood.