Reverse Osmosis Into Drain Under Kitchen Sink

[Al Roden]

Is this the proper way to terminate a RO under sink system to the drain?

[Mike Kleisch]

I've only seen a couple RO's and they were installed on the vertical drop below the sink and with the saddle clamp supplied by the manufacturer.

I would be more worried about the "S" trap flowing into the big "U" configuration. Not sure about your local requirements, but here you have to have the garbage disposal on a separate trap. That sink must clog up on a regular bases, or drain slow... :confused:

[Al Roden]

Maybe the flex connector is designed to slow down the water to stop the siphoning ;). Seeing the "S", the flex, the D/W drain and all the RO hoses weaving around in there had me wondering if maybe the RO hose to the drain is wrong too, but I don't know enough about RO to know.

It also has me questioning the quality of the water - there're RO systems under the bathroom lavs too. Apparently, the homeowner didn't want to brush their teeth with well water.

[Raymond Wand]

What does the manufactures instructions state? Never seen that type of fitting on a r.o.

[H.G. Watson, Sr.]

Is this the proper way to terminate a RO under sink system to the drain?

In a word: NO!!!

[Al Roden]

Is the little drain port at the bottom of the water dispenser the backup safety to the check valve? It's got a buildup of sediment around it like it's been leaking - so, would that be water from the drain or well water coming out of that port?

Also, besides the obvious drain issues, what's wrong with this check valve installation on the drain? It's got to be installed somewhere, doesn't it?

I'm also questioning the adequacy of the water softener - there's a lot of scale buildup around most of the fixtures. I'm thinking that if the softener was doing its job, then they wouldn't have that - anyway, the softener looks kind of small and puny for this 4 bedroom house.

[Ron Hasil]

That is a valid connection for the RO, as long as there is an air gap. But the drain set up is all wrong. They put a tee on the discharge of the garbage disposal, and plumbed in the RO which is a no no. Also here in Illinois the disposal must have its own trap, separate from the other side of the sink. The RO should of been on the down pipe of the side of the sink without the disposal. Here in Illinois saddle fittings on water supply and drains are against code as well. S trap against code, and what ever they have teed under the s-trap with the flex line is not trapped as well.

Short version it is all wrong and needs to be redone.

[Steven Saville]

This entire "Rube Goldberg" mess needs to be removed. It looks like the waste line into the wall is just behind the disposal. So everything below this level is always filled with water. Surprised if anything drains at all!.. a real homeowner special. :shocked:

[Jim Turner]

I've been recommending these for years...

Amerigap Model 52 (http://www.airgap.com/airgapLargeImages/amerigap52_1.htm)

[Larry Morrison]

It looks like it is correct according to the instructions that came with my RO Unit. I have never seen that type of fitting. Normally the RO Units will come with a simple saddle and the drain line is recommended to go on the top of the horizontal leg (as this one is) or can be on the side of the (a) vertical leg, Before the Trap. The rest of the piping?

[Mike Clarke]

That drain trap configuration indeed 'should' be changed, Do not like the use of flex either.

For where I am most garbage disposals are configured this way, no separate trap required here either.

As for having RO in bathrooms, the comment not wanting to brush their teeth with well water, in 99 percent of the time I will take well water over municipal water anytime :-)

[Dan Harris]

It looks like it is correct according to the instructions that came with my RO Unit. I have never seen that type of fitting. Normally the RO Units will come with a simple saddle and the drain line is recommended to go on the top of the horizontal leg (as this one is) or can be on the side of the (a) vertical leg, Before the Trap. The rest of the piping?


I've been under the impression saddle clamps are not permitted.
Per the (2006 International Residential Code P3003.2 #6, Page 453)
The following types of joints and connections shall be prohibited: …(6) Saddle type fittings

[Mike Kleisch]

I've been under the impression saddle clamps are not permitted.
Per the (2006 International Residential Code P3003.2 #6, Page 453)
The following types of joints and connections shall be prohibited: …(6) Saddle type fittings


Unless they are approved by the AHJ, then they are installed according to manufacturer's instructions.