flexible drain line & P trap ?'s

Is the flexible drain line permissible for this sink?

Also the two sinks have one P trap between them? Is that ok?

P3002.3.1Drainage.Drainage fittings shall have a smooth interior
waterway of the same diameter as the piping served
. All fittings
shall conform to the type of pipe used. Drainage fittings
shall have no ledges, shoulders or reductions which can retard or
obstruct drainage flow in the piping. Threaded drainage pipe fittings
shall be of the recessed drainage type, black or galvanized.
Drainage fittings shall be designed to maintain one-fourth unit
vertical in 12 units horizontal (2-percent slope) grade.

Is the material one of those listed in the table? I don’t see ‘synthetic rubber’ listed. Neither is ‘radiator hose’.

“2009 IRC P3002.1 Piping within buildings. Drain, waste and vent
(DWV) piping in buildings shall be as shown in Tables
P3002.1(1) and P3002.1(2) except that galvanized wrought iron
or galvanized steel pipe shall not be used underground and
shall be maintained not less than 6 inches (152 mm) above
ground. Allowance shall be made for the thermal expansion
and contraction of plastic piping.”

First off, those are not professional installations, which should be the first “red flag.”

In the first picture, the flexible trap is actually a listed component. However, it has been improperly installed, which has deformed it and rendered it ineffective.

In addition, the corrugated piece that it is attached to is a “tail piece,” which is for vertical use only. However, these are not approved by any model code for the reason Joe posted above.

In the second picture, the two corrugated tail pieces are wrong (which we have already established), but two sinks on one trap is perfectly acceptable. In fact, under the UPC, it is required.

I would simply report the drain lines to be unprofessional and improper, and recommend correction by a qualified plumber.

How can you tell from the photo whether or not it is listed? Are you just familiar with it? (I’ve never seen that material before.)

I am familiar with it (I’ll see if I can locate the info), but I don’t endorse them. I recommend replacing them whenever I see them because they are easily deformed by objects placed (stuffed) under the cabinets.

edit to add;


The corrugated tail pieces are in the vertical position on the second picture so they are correct? What am I missing?

From Joe’s post above:

Marcel posted this a few days ago on another thread:



Fixtures shall not be double trapped…

A single trap shall be permitted to serve two or three like fixtures limited to kitchen sinks, laundry tubs and lavatories. Such fixtures shall be adjacent to each other and located in the same room with a continuous waste arrangement. The trap shall be installed at the center fixture where three such fixtures are installed. Common trapped fixture outlets shall not be more than 30 inches (762 mm) apart.

In the second picture they appear more than 30" apart.

Would anyone be concerned and write that up?

They were installed the way they were intended to be used, but they are not an approved fitting.

Jeff I agree with you and I run across those often (the corrugated plastic fittings). I always call them out as non approved fittings. But, I’m curious as to why are the box stores even allowed to sell them?



Because someone will buy them.

Quick fix until the plumber arrives.

Greg is right.

Think about it for a moment. There are thousands of products sold in stores across the nation that should not be used for “home repairs,” yet they are sold to the public anyway. It’s just another reason why we will continue to have a job. :wink:

Yes, I see your point.