How to connect an RO drain to a garbage disposal
Connecting an RO drain requires choosing between attaching a drain saddle to the vertical pipe coming out of the disposal or routing to the lower P-trap. Because the trade-offs between these approaches and the risk of internal backflow are unclear, people get stuck trying to figure out the proper way to install it without damaging the drain tubes.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
- 1Drilling into the drain pipe above the P-trap directly below the garbage disposal
- 2Using an AirGap drain line adapter along with the dishwasher outlet and RO drain
- 3Dumping the reverse osmosis drain line into the P-trap where the dishwasher connects
In their words
Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.
“I want to install an RO system that can potentially prevent backflow internally, and want to install it with a garbage disposal unit.”source ↗
“What’s the recommended way to do this? It looks like there are trade-offs with both approaches that I don’t understand.”source ↗
“Could I add my reverse osmosis drain saddle to the vertical portion of the black pipe coming out of the garbage disposal.”source ↗
“The vertical pipe has the drain tube going in it. So could I Add it there without damaging tube? Or would I dump on the lower p trap?”source ↗
Where this came up
People with this problem also raised
- 7How to hook up a dishwasher drain hose under the sink
- 14Where do I run the vent for a washer installation?
- 4Why does the drain snake keep coming out the other drain?
- 2Are quick-release oil drain valves worth it?
- 9Does every sink need a P-trap?
- 3Washing machine drain pipe keeps leaking after putting back on