View Full Version : What is this hole for and why is water flowing out of it?

Mike Chance in Iowa
02-05-2018, 7:12 PM
We had a whole house water filtration system installed a little over a year ago and the RO faucet has always seemed rather delicate. Last night I heard sounds in the kitchen and discovered the RO water faucet they installed had water flowing freely out of the hole with the arrow pointing to it. (The round hole in the front of the faucet used to have a sticker over it that promptly peeled off a few weeks later...)


When I turned off the water valve under the sink, the water stopped flowing out of the hole. Turned on the valve, and once again water flowed freely out of the hole and thankfully into the sink.

I guess the big question is, do I need to replace the faucet, or is something loose inside the faucet to cause the water to flow out the hole?

George Bokros
02-05-2018, 7:17 PM
My RO water faucet has either a plug or a plug with a sticker over that whole but anyway it should not have water flowing out of it. I would contact the installer and find out their answer and solution. I would press them on a unit only ~ a year old to replace the faucet free of charge.

Marc Jeske
02-05-2018, 7:35 PM

Brad Adams
02-05-2018, 8:00 PM
That is the air gap for the drain. Take off the drain saddle under the sink and clean the opening.
There is nothing wrong with the faucet. It is a five minute fix.

Mike Chance in Iowa
02-05-2018, 8:31 PM
Thanks for the responses. Air Gap hole. That makes sense. I have a feeling there is some algae build-up or something in there. Weird stuff grows in those pipes!

Bruce Wrenn
02-05-2018, 9:36 PM
I have a feeling there is some algae build-up or something in there. Weird stuff grows in those pipes!Remember that's the water that you drink. For a REAL shock, go look in toilet tank. Tank, not the bowl.

Brad Adams
02-05-2018, 10:51 PM
The drain saddle on the tubular pvc drain fitting usually gets bumped out of place when shoving stuff under the sink.
The air gap is there to keep the gross stuff from backing up into the ro system if the drain should get clogged. The ro drains some water while it is recharging as you can only squeeze so much water through the membrane at a time.

George Bokros
02-06-2018, 8:14 AM
My RO unit is in the basement with the storage tank. The drain from my RO unit goes from the RO unit to drain in the basement and only one line goes to the faucet to supply water. My question to the OP is where is your unit located and suggest you look under the sink and see how many lines actually run to the faucet,

Myk Rian
02-06-2018, 3:35 PM
Remember that's the water that you drink. For a REAL shock, go look in toilet tank. Tank, not the bowl.
No. The REAL shock is what's inside your water heater.

Mike Chance in Iowa
02-06-2018, 6:33 PM
I have not worked much with plumbing so things are more doohickies and thingamajigs. There were 3 blue hoses going to that faucet and 1 led to the drain pipe. There were 2 quick-connect elbows at the drain saddle (thanks for that part name Brad). There was guck clogging the elbow closest to the drain saddle opening. Everything is working great now.

The house we are currently living in was not what we wanted, but we needed to get into something quick. We brought our trusty Kinetico with us and swapped out the dead Culligan already in the garage. Our water was bad. A builder recommended a "water chemist" and he come out and diagnosed our water issues. He was torn between being scientific about his findings and saying "Wow I haven't seen water this bad in years!" and "I'm sorry but this is going to cost a lot to fix." and "I'm impressed the Kinetico was able to handle this much on it's own." We have the garage wall filled with several different filtering devices in addition to our Kinetico, and the area under the kitchen sink is filled with a RO unit and 4 cartridges. We have to change the pre-filter at least once a month. If you look in the attached photo, it is the white area on the right side above the twin "black scuba tanks." The case appears black but it is actually clear to inspect the white filter & "clear" water inside. That was last changed less then 2 weeks ago and is totally dark now.


One of our neighbors drove past while the garage door was open and he noticed all the new hardware. He said everyone in our little area frequently have to replace their well motors and the former owner of our house had already replaced the motor once already.

The water chemist actually recommended even more filtering hardware, but it was already costing quite a bit. Our toilet tanks were black when we moved in and the faucet water gray. They are clearer now.