If you can upload a photograph of the exhaust where it resides next to the AC condenser unit, it will help. Maybe all you need to do is finish the exhaust with an upside-down "J" duct (like you see along sidewalks done by the utility company). How close is the vent to the AC condenser unit is also relevant as lint is not good for the condenser coils.

^ ^ Yup, both of those points.

Picture is attached. The "J" joint is already in place, and pointing away from the AC unit (hopefully that's enough, since I didn't put in the vent, but I did just recently replace the AC, and would rather avoid damage to that.) :-)

I've checked the joint, and there's no obvious cracks or damage...not saying that I don't have *some* amount of water flowing in that way, but I'm averaging 2-2.5 gallons of water in the pipe every time I vacuum it out, so I doubt that would be the entire reason.

That's too close to the A/C IMO. You don't show the full unit, but most of them pull air through the sides of the coils when running and exhaust it out the fan at the top of the unit. It'll be pulling warm, linty dryer exhaust through the coils whenever the dryer is running simultaneous with the A/C. It may be somewhat OK but I wouldn't arrange mine as such.

You've got a breach somewhere in the buried PVC pipe that's letting in water.

Thanks! Three questions:
- What's the easiest way to fix the pipe? I have a friend who has mentioned a sealant you can spray into a pipe, but I don't know if that's actually a viable fix for PVC.
- Should I just knock off the end of the "J" and extend the pipe further away from the unit? Relay everything if I have to dig it up to fix the breach?
- Is there a safe way to just move the vent through the garage?

If the dryer vent line is filling with water after a rain, the pipe has been damaged. There are ways to fix pipes without digging up the slab but I'm not sure it would be cost effective for a dryer vent. You might want to look in another direction.

A few more questions:

• Where are you vacuuming out the water--at what point in the duct?

• Have to excavated the dirt around the outside exhaust to reach the underground elbow to determine whether it is glued in place and not just a friction-fit?

• If the pipe is glued properly then might want to have a plumber come out and use a video scope to see where the problem(s) is located.

• I see leaves in your photograph, invasive tree roots will seek water through any pipe joint that was not sealed correctly or any pipe that might have been cracked during installation.

• Does the end of the exhaust pipe have a critter screen?

• Check to see whether the exposed white PVC piping is UV rated.

This post was edited by fahrenheit_451 on Tue, Mar 26, 13 at 23:18