Reverse Osmosis drain backup

[J.Appleseed]

Hello, my kitchen sink drain pipe recently stopped up and flooded my sink. While I did stop using the sink, I continued using the RO faucet for drinking water that day, and could not figure out why the water level kept rising on the sink until I realized it was the backwash! The water flooded into the sink basin up through the drain, but was also coming out through the factory air gapped RO faucet. There is no air gap installed at the drain end of the backwash line. My question is did backwash water, or worse yet sewer water, potentially contaminate my RO filters? And if so, is there a recommended method to sanitize the system? Replace the filters?

 

[John Gayewski]

Sounds like it could've. You'll need to show a diagram of your piping to be more certain.

 

[Sponsor]

 

[Reach4]

Dunno. Logic says it is pressurized, so I am not sure if you need to worry about bugs swimming upstream. Further, I suspect there is a check valve. But I am not really knowledgeable on this.

"The water flooded into the sink basin up through the drain, but was also coming out through the factory air gapped RO faucet. There is no air gap installed at the drain end of the backwash line. "
I think the air gap is in line with the drain line. I doubt that the drain line built enough pressure to bring drainage up to the air gap. If there was that pressure, I would think you would fill and overflow the sink. I am picturing the drain line water not having a good place to go.

Does your RO have a backwash line? I am unfamiliar with a backwash line for an RO.

Yes. https://vcrma.org/docs/images/pdf/eh/disaster/SANITIZING-A-REVERSE-OSMOSIS-FILTRATION-SYSTEM.pdf is one of several write-ups.

You did not address if you got that drain cleared out. You might want to bring in a drain cleaning specialist, rather than poke thru the clog with your own 1/4 inch snake. Kitchen sink clogs often occur where the drain line transitions from vertical to horizontal.

 

[Jeff H Young]

Your R/o and potable water should / must be seperated from drain lines through an airgap or other approved method (check valve possibly)