Air gaps optional?

[maximum]

I was told years ago by a plumber that you "don't really need" an airgap for reverse osmosis filters (I was complaining about the drain noise). He told me how to hook the hoses up to eliminate the airgap, which I won't go into here because my question is: is this safe? Is this airgap really only there for when my SEWER backs up into my sink? If so I think I can live without it! Or does a sink clog backing up present some sort of flowback danger to my RO unit? Thanks in advance.

[trader4]

I think you know the answer to your own question. Air gaps prevent siphoning of waste water back into whatever is connected to the drain, ie dishwasher, RO, etc. Most dishwashers are not installed with one, though in some places code requires it. If an air gap is not used, for dishwashers, the drain line is routed high to the bottom of the countertop, to help prevent the problem. But that is not as good as an air gap.

For a dishwasher, I'd say it's OK. Mine is done with a high loop. However for a unit that handles drinking water, I would want the air gap and I would be surprised if it were not required by code.

[Robert Gammon]

Air gaps are a health issue, designed as described above to prevent waste water from mixing with potable water.

RO faucets on a sink have been sold for decades with air gaps in the faucet.

My RO output is plumbed solely to the refrigerator for Ice and Water.

My RO waste water goes to a sump pump that is common with the AC Evaporator drain. That then pumps to the clothes washer drain. I get pump noise every 10-15 minutes while the RO is refilling the tank, more often if the AC is running. sump pump is in a tub that connects to a separate waste water drain for AC only, in case the sump ever fails.

[Thomas Daniel Horne]

If you don't mind the possibility of your family drinking and eating raw sewage then forgo the air gap. If the thought of trying to decontaminate your filter system after such an event gives you pause then install the air gap and live with the noise.

[Robert Gammon]

The issue is that we tap DIRECTLY to a cold water line under the sink. RO drain water then flows DIRECTLY to the waste water drain in the sink. This is the noise that was being complained about.

If the RO fails, then the possibility is STRONGER that kitchen sink waste water contaminates drinking water than the risk of toilet water making it into drinking water. Either situation is EXTREMELY unpleasant and VERY unhealthful. But Sink drain water is much less likely to contain E Coli bacteria.

RO membrane failure is rare, but possible due to over pressure (very unlikely) or very hard source water clogging the membrane and possibly rupturing it (also very doubtful)

When I had my RO draining into the clothes washer drain, I had to carefully position the hose so that the constant gurgle of the waste water would not distract.

[Joseph Meehan]

I suggest that you check with your local code enforcement agency and with the manufacturer of the RO unit. If either say you need it, then you need it. clearly you would not have the unit if you were not worried about clean water. Why risk it, follow the rules and instructions designed to keep you safe.

[maximum]

You have convinced me. Thanks for your input - I'll replace the air gap and live with the constant gurgling. Better gurgling coming from my sink than my family's gastrointestinal systems!

[maximum]

You have convinced me. Thanks for your input - I'll replace the air gap and live with the constant gurgling. Better gurgling coming from my sink than my family's gastrointestinal systems!