Depending on location and whats involved, sometimes tunneling under the slab to run water lines is succesful.An experienced plumber knows this method. Appearently your plumber isn't.

Another method instead of breaking out the jack hammer is to saw cut a channel in the concrete to run the lines. It all depends on your situation and location on what approach will work, but saw cutting a channel is a cleaner, less involved solution if doable.

We're putting columns on our island.

The link below is a picture of a secondary island with columns.

Ours will not be this design, but the picture may help you visualize what yours may look like.

Here is a link that might be useful: Olson Residence

I recently ranted on another forum about the painters who painted my house EXTERIOR using INTERIOR paint. An innocent, but very careless error on their part. Then came multiple lies to try to get me to accept it and to try to shift the blame to the paint store. It is now is resolved about as well as possible- it cost them a lot of extra material and labor.

This is deja vu.

This exact post was made 1 or 2 years ago hear.
I think they ended up tunneling for their solution.

Jimonthebeach - You're scaring me. I hope your plumber isn't my plumber. Although there is necessary piping in the kitchen, the idiot couldn't get a darn thing right in my shower.

No kidding, what's with these people!

I went to the house at lunch, and they have a third option... which I chose. They will use the pipe that was supposed to be used for a vent, for the water line, and then use a pro-vent (?) for the sink. They will still have to break up the concrete, but it will only be under the island. Any DIY plumbers that know what this is?? I hope it works!!! Time will tell.

The pro vent they speak of is an air admittance valve that isn't allowed in all areas of the country.I dont think they would go that route if it was against code but i would double check.If the vent is schedule 40 d.w.v. pvc material, i would be a little concerned using that for a water line.

The time will tell attitude is a no go. Now is the time to get it right so you wont have future problems. I would get some advise from possibly another reputable plumber in your area, which will probably be a service charge to sneak a peek, but worth it.

It's also called a "studor vent", "remodel vent" or a "mechanical vent". Home Depot sells kits that include the p-trap and what-not for installing sinks. You can see a picture of how it's installed on one of those kits.

In a nutshell, it's a cap that allows air to draw into the pipe but will not allow air in the pipe to escape.

In one of my "stupid code enforcement" rants, we had to install one in a virtually useless place to get our main line officially classified as a "main vented line". We also purposely installed one in the basement wet-bar, as venting the sink would have been way too difficult. They're in use everywhere Plan A (a real vent) is impossible.

So they had a drain line, and a vent line going underslab to the island area? Not sure how that vent wouldve worked anyway, under that application.

Iteresting that they had the drain in, but no water lines.

Islands require the use of a loop vent usually assembled after cabinet install.

Still not getting the use of a vent for a water line(s). Hopefully the op will keep us posted.

Everyone understands that plumbing vents allow the stinky, obnoxious, & toxic sewer gasses to safely dissipate into the atmosphere however that is just the small part of what vents do.
As liquids pass through the drain and waste pipes it displaces the air, which is present in the line by pushing the air ahead as it moves. If a drain line is sized correctly a horizontal pipe should only be full under full load. This keeps the upper half of the line open for the transfer of vent air over the liquid and into the space behind the moving liquid. In this manner the air pressure in the line will remain constant, however, there are conditions where the upper half of the line may also be obstructed by the moving liquid. Under these conditions as the liquid moves forward it leaves a partial vacuum behind the liquid which would then suck the water out of the fixture trap, thereby leaving the trap open for sewer gasses to enter you house once the liquid has moved on to the sewer.
In order to prevent that partial vacuum situation the Plumbing Codes are very specific about where and how vents are to be placed. In fact, ask any plumbing inspector and he or she will tell you that venting is the most important part of the plumbing system, and the part which gets the greatest scrutiny during a plumbing inspection.
Now to answer your question, the terms "Pro-vent, Studor Vent or Cheater Vent" are trade names for a device, which is properly called an "Air Admittance Valve or AAV). An air admittance valve is a device, which has an internal spring-loaded diaphragm that will open under negative pressure and allow additional vent air to enter the pipe. The singular drawback of the AAV is that they will allow additional air into the pipe to protect the water level in the trap seal, but they do not allow the sewer gasses in the pipe to safely escape to the atmosphere. For this reason the use of AAVÂs should be limited.
Under the International Residential Code (IRC) all structures are required to have one "Main Vent" which must run undiminished in size from the building main drain through the roof. After that is achieved you may terminate additional auxiliary vents in the attic space, through the wall under very limited circumstances or you may use an unlimited number of AAVÂs
Under the Uniform Plumbing Code (UPC) ALL VENTS must terminate through the roof, however the UPC will allow a maximum of one AAV per structure.
Based upon information presented in the original post this homeowner is under the UPC, and while it is legal to use the AAV or in their case "Pro-Vent" it is understood that this is the only one that may be used in the structure.

------Caroline emailed me direct and asked if I would accept the "Pro Vent" I thought the question was important enough that i would like to share my response to all.....

I am sure that many people who read my reply are left wondering how did I conclude that you are under the Uniform Plumbing Code (UPC) rather than the International Residential Code (IRC).
The answer is that this is an island and it appears that your plumber originally intended to vent the island by means of an "Island Loop Vent" which is the preferred method of venting island fixtures.
Under the IRC to create an island loop vent we attach two parallel vertical risers on the upstream end of the drain line at the island sink. The sink drain is attached to one of the risers and both risers are interconnected at the top forming a loop from the drain below. (There is no vent line under the floor)
Under the UPC we also install two vertical risers as described above with the sink drain attached to one of the risers. On the top of each riser we then install a 1/8th bend (45deg sanitary elbow)and angle both pipes up at 45degress until they meet at the top where they are connected by means of a 1/4bend (90deg sanitary elbow). The UPC then requires that we install a vent on the riser opposite the sink connection and this vent line runs horizontal under the floor and back to a regular vent riser, which goes up and through the roof. This is the only situation in which the code will allow a horizontal vent below the flood level rim of the fixture served by that vent.
The IRC allows an unlimited number of AAVÂs therefore most plumbers simply use an AAV to vent an island rather that go to the expense and bother of making a proper loop vent.
The UPC only allows a maximum of one AAV per structure with the expressed consent of the local inspector therefore under the UPC it is common practice to install a proper island loop vent rather than the AAV.
As I am sure you will agree, everyone makes the occasional mistake and in this situation the mistake was forgetting to run the water line. The true measure of a tradesman is how well they can correct the mistake without causing additional problems on the job and when I read your plumbers solution to the problem of the missing water line I personally thought it was a rather ingenious. He, or she as the case may be, has opted to use the AAV to vent the island, which is fully code approved. Having done that, he or she is now free to use the horizontal vent line under the concrete as a conduit to pull in the missing water line thereby precluding the necessity to cut the concrete.
Under the circumstances I would give your plumber two thumbs up for a great recovery.

But then what do i know,,I am only a Master Plumber

Now i get it. Glad it all worked out for teach!

Hey, lazypup, thanks for the detailed info and professional perspective. It's nice to have a clear picture and know an adequate resolution has been made every now and again.

Actually in years to come this could prove to be a plus for you.

You stated in your post that they originally forgot to install one line, however a sink has two, hot and cold so I am assuming that perhaps one of those lines was run under the slab in the conventional manner. Depending upon what kind of pipe they used to run that line, it could fail from contact with soil acids over time. In the event that should happen you already have a conduit which would allow them to simply pull in a replacement line without cutting the floor.

In fact, if I were building a house with an Island I would run a 3" PVC conduit from the island to a wall space under the cabinets or to a utility space then pull roll copper or PEX through the conduit to make final connection. In that manner you could easily change a line without damaging the floor.

Lazypup,
I think there was only one line of pvc run to the island... originally for the vent. Can the hot and cold lines of PEX be run through the same PVC pipe?

The vent line is a 2" schedule 40 PVC line which has an internal diameter of 2.047".

The supply lines to a kitchen sink are either 1/2" copper or 3/8" PEX tubing.

The could easily pull two runs of continuous roll copper pipe or PEX tubing through that 2" PVC pipe.

Why can't people just do their job right??????

I don't know. I think all the quality and professional pride has been lost and replaced by the lowest price concept. You can't even find anyone that's able to read a set of prints anymore.

Can I use a AAV on my washing machine drain? It drains to a grey water fill outside home of course, it is not on sewer or septic drain, but I have no air vent to it. Occasionally it has backed up, if I babysit it and "burp" the line to allow the vacuum to release it will drain okay, I do not want to babysit it all the time. Will this AAV work for my situation?