Gurgling RO countertop system

[Brenton]

I recently moved into a new house and reinstalled there the reverse osmosis kitchen countertop system I have (Aquasana's OptimH2o Reverse Osmosis + Claryum Under Counter). Whenever it recharges/refills it makes a very loud gurgling sound. Another (perhaps related) problem is that the water flow is quite slow after the first quart/liter of water or so.

Aquasana customer support only suggested replacing the "flow restrictor," which is something one inserts into the 3/4" tubing to slow the flow of the water at that stage of the system. That did not help.

I surmise that the RO system is lacking air and that this explains both the gurgling (air moving through the pipes) and the slow flow rate. The sink plumbing itself is an S-trap rather than a P-trap, and it is not connected to an air vent (instead, it's connected beneath the flooring to the main plumbing line and from there to the house air vent). Perhaps an air intake valve would solve the problem?

The gurgling is extremely loud and annoying, and so I would be most grateful for anyone able to identify the problem.

I attach an image of the RO system setup under the sking. I have some short videos, too, but I'm not sure whether I can upload them here.

Thank you!
Brenton

 

[WorthFlorida]

I surmise that the RO system is lacking air and that this explains both the gurgling (air moving through the pipes) and the slow flow rate. The sink plumbing itself is an S-trap rather than a P-trap, and it is not connected to an air vent (instead, it's connected beneath the flooring to the main plumbing line and from there to the house air vent). Perhaps an air intake valve would solve the problem? Thank you! Brenton

For videos upload it to Youtube or another video site, then link it.

I would suspect that lack of venting of the drain as you seem to indicate. I would reconfigure the double bowl drain to this and you'll be able to change it to a p trap. Also add an AAV for venting. But before you tear it all apart, disconnect the drain line from the RO at the sink drain and run it into a 5 gallon bucket and run the RO to see what happens. If a hole was drilled into the tail piece for the RO drain, is it the correct size? This system was already under the sink but not connected? If yes the RO membrane is bad or one of the filters is clog up? Did Aquasana customer support indicate that the membrane is good.

 

[Sponsor]

 

[Brenton]

Thank you for your response, WorthFlorida! I removed the RO drain tube and allowed it to drain into a bucket. The gurgling ceased! But what might that mean exactly? Yes, I had drilled a hole into the tail piece for the drain, and I can confirm the hole is in the right place (where the RO drain meets it) by inserting a screwdriver through the hole. The directions for drilling the hole were to make it 7/32", which is slightly smaller than the 1/4" RO drain tube that meets it.

I didn't understand the following question: "This system as already under the sink but not connected?" This is a system I had bought and previously installed at another house. I only began to have this gurgling problem upon moving it to my new house.

As for the membrane, I just replaced it with a new one tonight. I need to let water run through the system overnight to clean it.

So, gurgling continues as long as the RO drain tube is connected to the tail piece.

14 sec. video of the problem (gurgling):

23 sec. video of low water pressure + gurgling:

24 sec. video of air passing through the RO drain tube:

38 sec. video showing the ceasing of the gurgling when RO drains into bucket + some resumption of gurgling:

 

[WorthFlorida]

A slight typo, to ask if this was a used one and it came with the home was my question. At least you know that it did work at one time. With the drain line disconnected there is still air passing through so somewhere air is entering the system and not caused by a non vented drain. Removing the drain lessens the back pressure some so the air and water passes more freely. In the videos it sounds like a motor is running, really strange.

I watched the installation video, done very well. It'd be probably impossible that the two red tubes are reversed since they are sized differently. The red from the system is the output or waste side and it goes up to the faucet housing? I think the faucet connection (housing) is acting as a air gap, similar to a dishwasher air gap. I would remove the red tube to the faucet and bring that to the bucket and try it. I presume that you did the purge procedure.

 

[Brenton]

Thank you, WorthFlorida! I'll try what you suggested today and report back.

 

[Brenton]

I ran to a bucket the red hose that comes from the the manifold and runs to the RO faucet. This stopped the gurgling. I also tried running the white tube coming from the system (running form the final stage of the system, after the manifold) to the RO faucet. The gurgling seems to have *intensified.*

I redrilled the hole in the tail pipe to make sure it was perfectly round and I also adjusted the drain connector to make sure it was centered over the tail pipe hole.

At some point the gurgling became more muted--it didn't stop, but it wasn't as loud.

I've was also able to stop the gurgling at one point by holding the RO drain system completely vertical against the sink drain pipe.

The "motor" sound is the RO system. I had assume that was normal behavior, but maybe it's not?

So, I think you're right that air may be getting into the system via the RO faucet. Perhaps I should just have Aquasana send me a new RO faucet?