What is this drain pipe/vent?

There is a drain pipe/vent that exits the garage area next to the side door that leads to the side yard. I never really thought to find out what is was for until now because it has been dripping water. At first it was a slow drip and now it is much faster and is starting to pool up in the saturated soil. What is this drain pipe/vent? Why is water suddenly dripping constantly? Where is the water coming from and how can I most likely stop the leaking? Thanks a lot for any input!!
q what is this drain pipe vent, curb appeal, hvac
q what is this drain pipe vent, curb appeal, hvac
  14 answers
  • Keith Keith on Mar 12, 2014
    Hey Kevin, I'd offer up two strong possibilities. It allows the condensation that builds up on HVAC systems to drain off, if so, it's doing it's job. The other would be it's a drain from your hot water heater, likely indicating a problem. Either your hot water heater is going bad (causing leakage) or your pressure relief (or pop-off) valve is leaking. Those could cause you serious issues with water damage. You really need to trace the line back to where it originates.
  • I would agree the AC condensate pipe. If it was a hot water heater, I would assume there would be steam coming off the water if its hot. To small to be over flow drain for washer if located on 2nd floor, these are usually 2 inch pipes.
  • SDair SDair on Mar 13, 2014
    I would add to the above comments. The drain is consistent with being either a condensate drain for the air conditioning or the high pressure valve from the hot water heater. To find out which one, shut the water supply off to the hot water heater, then check to see if it is still dripping. If it stops, then it is likely the hot water heater. Just open and close the pressure valve, which may re-seat it and correct the issue. If it doesn't, replace the valve. If you determine the drain to be from the air conditioning, you should look at your indoor equipment. In some areas, there are 2 drains coming from the indoor equipment. The first is the primary. If you only have one connected, this may be that one. If you have 2 connected, this is likely the secondary drain. I mention this because the primary likely goes directly to a sewage drain. The secondary is a safety drain, for when the primary drain becomes clogged. When this happens, water then drains through the secondary drain to outdoors. If this is your secondary drain, you need to clear the impediment in the primary drain. Once that has been done, you should no longer see any water coming through this drain.
  • Steve Steve on Mar 13, 2014
    I vote that it's your air conditioning condensation drain pipe... at least that's what they look like down here in Orlando... (a word of advice Kevin... don't let it get clogged-up, your A/C room or area will flood & what a mess -Wooooo !!!)
  • Kevin Mariant Kevin Mariant on Mar 13, 2014
    Thanks everyone! This information is very helpful. The HVAC drain is in the front yard so I know it isn't that. The water heater seems like the likely culprit (water heater is directly in line to where the drain exits the house). I will take a look at the pressure valve on the water heater. Hopefully that will solve the problem. The water heater is surely on its last leg, but hopefully I won't need to replace it just yet. When I bought the house almost two years ago the inspector said it could go out in a week or last a few more years. What is everyone's thoughts on a 50 gallon water heater vs a tankless water heater?
    • See 2 previous
    • Becky Greenwald Becky Greenwald on Mar 12, 2015
      Tankless is awesome. You may never recoup the investment, or you may, but you won't have a tank of hot water sitting around to worry about. I love it.
  • Hot water heater would be steaming anyway. Also the drain pipe would be 1 inch not 3/4 inch on overflow pan for that device.
  • Charlotte Belange Charlotte Belange on Mar 13, 2014
    I agree with all the above. I think its a water heater pipe if it is wetting the ground that much the heater needs to be checked, then put in more dirt all a long the wall and plant a good ground cover. Char B YELM,WA
  • Kevin, depending on where your water heater is located, it may not be wise to take it to failure. If that baby lets go in the wrong place at the wrong time, the savings you think you made by milking it to the end will be far out-weighed by the cost to repair all the potential damage. Keep in mind it isn't just the water in the tank; the tank is pressurized by the water pressure in the house and it will just keep coming until it gets shut off. As far as a tank system versus a tankless system; lots of different opinions... and with most issues there is data to back up both sides depending on your individual circumstances. Don't even consider the switch unless you are thinking a gas unit. The technology isn't quite there yet to make an electrical unit efficient enough to compare. To best answer your question, add another post or it will be "hidden" in your original; or do a search here on Hometalk for "tankless" and you will see more opinions than you ever asked for. Keep in mind the contractor and supplier types make more profit if you choose a tankless over replacing a like-like since it involves so much more work for the initial install; that may influence their opinions. For my own house, I figure it would take 12-15 years for me to recover the cost of installing a tankless system over a new energy-efficient tank unit.
  • Dee Dee on Mar 14, 2014
    What ever it is needs a hose to move it away from the house or you may have bigger problems down the road with your foundation/water in your basement.Good luck to you.
  • Pete Wells Pete Wells on Mar 14, 2014
    I agree this is most likely from the T&P valve on your water heater, which would be 3/4" ID copper or CPVC...if your water heater is due for replacement anyway, changing the valve would most likely be a waste of time & $..I've also seen this problem caused by too high incoming water pressure...in which case you should be happy the valve is working properly! If you change the water heater and still have dripping from this pipe, the water pressure needs to be checked...this problem is more common than many would believe...
  • Neva Dew Neva Dew on Jul 24, 2015
    I know this post is a year old, but if the water heater is gas(natural or propane) there has to be someway for the by-product of the combustion (H2O) to drain. Didn't see that mentioned.
    • Pete Wells Pete Wells on Jul 25, 2015
      @Neva Dew the 'by-products of combustion' on a gas water heater are exhausted through the flue, usually via a 3" metal vent pipe from the top of the water heater..
  • Neva Dew Neva Dew on Jul 25, 2015
    Yes, the gaseous by-products exhaust thru the vent - but we have gas heat and water heater and all also have pipes to take away the water that is result of combustion -the water heater has not released water thru the release valve thing in the 10 years we've had it. I really do think I'm right on my science here.
    • Pete Wells Pete Wells on Jul 26, 2015
      @Neva Dew If your water heater has a metal flue, as most do, all your combustion by-products exhaust via your metal flue...newer, 90% efficiency furnaces vent with PVC pipe, and require a drain for combustion by-products...if your water heater has a plastic flue, it, too, will require a drain from the secondary heat exchanger...but not if you have a metal flue...Have installed many furnaces and quite a few water heaters to boot..so, if the water heater has a metal flue, the only drain connected to it is for the T&P valve..which must not be tied in with any other drains, if it is, you need an HVAC contractor to correct a code violation...
  • Miles.j Miles.j on Jul 25, 2015
    My relief valve for water heater and condensate drain from A/C Tee together in the utility room then goes outside. It could be from either.
  • Mar6469154 Mar6469154 on Oct 16, 2016
    Maybe it is from your ac unit