Okay, new here and possibly losing my mind. There is a puddle at the NW corner of 7th Ave and Greenwich that has been there through four completely dry days. Not a little damp spot—like a full shoe-soaking puddle that catches people turning right toward the pharmacy. I’ve watched three people almost roll their ankles stepping around it. Is this a known leak? An old underground spring? A building AC drain that never stops? I’m half considering timing how long it takes to reappear after street cleaning. Has anyone else noticed this or do I just have bad corner luck?

Lol I know exactly the corner. That puddle is basically a permanent resident at this point. My money’s on a building sump pump or a basement dehumidifier draining through a little pipe behind the garbage cans. Those things can weep all day. Walked through it once in canvas sneakers and was mad for hours. Check the curb near the tree pit after dark, you'll see a slow trickle coming from a black hose.

A few possible culprits, in order of likelihood:

• A condensate drain from a refrigeration or air-conditioning system. Delis and pharmacies sometimes run vinyl tubing from a cellar to the curb, and it drips constantly even on low-humidity days.
• A leaking service line valve under the sidewalk. Those can produce a surprisingly persistent wet spot without a visible spray.
• A broken catch basin or sagging curb that holds stormwater for days. If the puddle is in a depression, the water may be rainwater that simply can’t reach the drain.

The best test is to look up after dark or right after street cleaning. If the street is fully dry and a small trickle is still feeding it from the building side, it’s mechanical runoff. You can report it to 311 as a non-emergency water condition. In my experience DEP doesn’t always close it out quickly, but a photo with the exact address helps.

Also, not to drag us too far off topic, but for the people who were looking for the older Knicks road game with sound in Bay Ridge/Dyker — is that too much to ask? thread, the discussion is here: Knicks road game with sound in Bay Ridge/Dyker — is that too much to ask?

I’d be a little cautious about calling it a hose or normal AC runoff. I tracked a similar puddle on my block for two months and it turned out to be a cracked water service box in front of a small apartment building. The water only surfaced when the basement circulation system cycled. The key is whether the water is cold and clear or slightly soapy/murky. Clear and cool leans plumbing or groundwater. A faint laundry or mop-water smell leans basement sump. Don’t bother testing it with food coloring or anything silly, just photograph the same spot at the same time two days apart. If the shape changes but never fully dries, the source is active rather than trapped rainwater.

Ha, the real petty test is whether it’s a puddle or corner slush from a bodega ice machine dump. I used to live over there and that pharmacy block always smelled faintly of mop water. Honestly if it survives garbage pickup it’s probably not the stores. Still, I’d rather dodge that puddle than the e-bike goons on 7th. 311 app actually has a water-on-sidewalk category, takes two seconds, but nothing moves fast.

Thanks all! I did the after-dark walk and saw a pencil-thin stream seeping from a crack near the basement grate, not a hose. Water looks mostly clear but the sidewalk is stained green around the joint. I sent a 311 report with a close-up of the curb and used the water leak category. Now I’m annoyed because the puddle was gone for maybe two hours after street cleaning but came back by morning. Is that a sign it’s pressure-driven, or just gravity doing its thing?

Ooh, green staining is the big clue! That’s usually copper oxidation from condensate or from a very slow pipe drip, but not always. Have you tried photographing the same spot at 7 a.m., noon, and 10 p.m. from the same angle? The rate of pool expansion tells you a lot. I did this once for a weird puddle on Jay Street and it turned out to be a misaligned downspout behind a dumpster—nobody looked up! If the crack is on the building side, press your phone camera right up to the grate and see if there's a pipe discharge. Also, is the puddle slimy or just wet? Slimy means organic runoff, just wet means mechanical or plumbing. I love these tiny drainage mysteries. Have you tried checking the DEP waterbody maps or the DOB permits for that address?