Check the venting system. It may be blocked or not even connected.

The vent is not blocked and it is connected. Thank you for the suggestion, though.

I can only think there's a problem/blockage with the drain itself, or - I'm not sure what you'd call the reverse of an airlock - but air's not drawing properly.

I guess it's certainly possible (especially with all these wild, themed vanity sinks out there, that it just isn't much for draining, but I suspect something else is wrong. I assume there's a built-in stopper, you might want to verify that's connected and aligned properly.

Did you install an umbrella or pop-up in your vessel? Sometimes the unbrella will capture air and restrict the water discharge. Try removing the umbrella to see if water discharges. If it does, then you will know the cause.

It doesn't have an umbrella drain, just a drain that is open. It just has holes in it. I think the problem lies in not having an overflow. There is a suction somewhere. It drains to a certain point, then stops. If I break the suction by pushing my hand on the holes in the drain, air comes out from the drain and then the water drains. My carpenter, granted he is not a plumber, suggested that I need air in the pipe somewhere.

The plumber hasn't been back, but it was his (inexperienced in vessel sinks) son who put it in. The plumber wasn't there and the son said he would talk to his Dad about it. I sure love the sink and hope there is a solution. I have two more no overflow vessel sinks ordered for the master bath and I am wondering if I should cancel that order.

Hello minnt,

I doubt it is because your vessel doesn't have an overflow. I have several vessels sinks and so do many of my friends and family (none have overflows). In all cases, drainage is not a problem.

If your vent is operational, there is no more that an overflow would provide with respect to ventilation... What I would focus on is the height of the P-Trap and it's relation to the drain pipe elbow in the wall. It seems like your problem is more about a lack of flow through the drainage piping. Is the P-trap too close to the sink? Is the "tail pipe" at a slight downward angle towards the "T" where it connects inside the wall? Your plumber should take another look and make sure that everything is configured properly.

Good luck!

I had the same problem with a vessel sink in our powder room earlier this year! I had installed it myself, and although everything seemed straighforward enough, I couldn't figure out the problem. What was really bizarre was that the bowl would fill and fill while only draining slowly until the bowl got about 75% full -- and then suddenly it would suck down very quickly similar to the way a toilet bowl empties, or a sink you've just blasted with a plunger.

I called in a plumber -- who was also puzzled. After consulting (by phone) with his boss, they added a T fitting to the tailpipe and attached a piece of pipe to draw in air; the end of this pipe has a gizmo which allows air to flow in but prevents water from backflowing out. By pulling in air in addition to the water, it did make a significant difference. I'm still not convinced it flows as quickly as it should, but at least guests don't get concerned that it will overflow! The plumber said this sink should probably have a wider drain pipe, but I didn't want to get into replacing all the plumbing I and he had just put in, so we just left it at that point. The extra "T" for pulling in air is probably something your plumber could try fairly easily to see if it solves your problem or (helps enough).

-- Eric

First, some sinks work fine with no overflow. It depends on the drain pipe layout and proximity of the vent pipe. Normally, the gas vent pipe in your roof will allow the air to escape.

Do a test. Remove the trap and sit a bucket there. Run water in the sink. If it drains fast to the bucket you have an air block issue and need venting or a different drop.

If still slow draining, the issue is surface tension. Replace the drain with one having larger holes or slots. There is a critical hole size that varies with your water's hardness.

About two years ago I installed two vessel sinks with grid drains and had drainage problems from the beginning. I searched the web including this site and after evaluating all alternatives, I came up with a solution for me.
My grid drains have 3/8" holes in them so today I took a 1/4" drill bit and opened up five of the holes to make a nice pattern. The center hole and four others.
I didn't even have to take anything apart. I just drilled while it was still in the sink and washed the filings down the drain. I did take a small round file to smooth out the holes. It took less than five minutes for both grid drains. Now everything's fine.

In addition to the solutions above, when you have no overflow option on your vessel sink, try turning the faucet so that it doesn't aim directly at the drain. You will create a flow in the water pattern that allows it to drain faster in a "whirlpool" motion. Easier than some of the solutions above, but might not work for shallow bowls. Mine is quite deep.

I put four non-overflow vessel sinks in my house. All drain slow and have the same issue as most of you. It is not your plumbing or venting. I read of a solution on another site whereas he installed a automatic air vent on the tailpipe before the p-trap. I did it and it works great and doesn't have a chance to leak water.

You probably have 1 1/4" tailpiece going straight down. You will need a Watts automatic float vent p/n 4a821. Need to get it from a plumbing house. A3/8" MIP x 1/8" FIP pipe bushing (lowes/HD), 1" x 3/8" pipe bushing (Lowes/HD), 1" PVC compression tee, 1" PVC elbow threaded.

Attach the Automatic Float vent to the smaller bushing, then that to the bigger bushing, then that into the elbow, that into the compression tee. use teflon tape on threads. Remove the tailpipe and cut it in half removing about 1.5" of pipe. slide the two pieces into the compression tee leaving the 1.5" gap and hand tighten. Make sure the float is upright. open the black cap on the vent 2 turns. Install the tailpipe back in line and hand tighten those plastic nuts.

Test out the system. it should work fine and cannot leak as the valve has a float in it that allows the trapped air out and blocks any water from escaping.

" It is not your plumbing or venting."

If adding a vent fixes the problem it IS your venting.

And I doubt that setup complies with the plumbing code.

Your almost right there Brickeye,,,it is a venting problem...but not the plumbing vent. The plumbing vents are on the downstream side of the trap and they only effect the flow in pipes from the trap on down.

The problem is exactly as it was explained above. When the drain stopper is opened the entire drain tries to fill with water, while the static air in the tailpiece retards the flow. Watts developed that valve to take the place of the overflow and allows the air out.

and for the record,,,that valve is the code approved solution to the problem.

We did a version of fireman 175's solution and it worked great!! Knew we had a venting problem when a straw stuck in the grid drain of our non-overflow sink solved the slow draining issue.
Thanks fireman 175!

Had the same problems and found all these solutions on this forum. Went with two little holes above the tail piece and it works great. A quick solution with no leaks, drains quickly, and NO COST or extra plumbing. Now that's my kind of solution! Thanks pliesj.

I have had this problem for a year now in my new glass vessel sink . The sink was looking awful all the time because the soap would stick to it while the water was draining slowly. Thanks to the solution suggested by pliesj , of having two holes in the pipes , I have a great looking sink with no soap scum ..

I had the same problem with my vessel sink and adapted the previous post to install a "studor" vent above the p-trap with parts available at Lowx's or any local store for about $17. Now it works like a champ! Please see pics.

I'm so glad I found this thread! I've had an overflow-less undermount glass sink for 7 years with a slow drain problem. Doesn't sound quite as bad as some here but still much slower than my old Kohler cast iron sinks w/ overflows. I've never done anything about it and it's really not a HUGE issue as I'm the only one that uses the sink. Seven years later and we're redoing DH's bathroom with the same type of sink. It WILL be a problem for him so I need to find a solution, quick! Plumber is coming on Monday. I'm sending him this thread.

Stupid question: How in the world could you have an overflow in a vessel sink? Where would the overflow water go? Out the side and onto the counter?

I've wondered the same thing LOL

Unless you had a double-walled sink and the overflow would run out and between the walls. But that would probably be fraught with more problems than the single-walled sinks have.

Actually, that is what my bath vanity sink with the big protruding "belly" did. It had a hole for an overflow, double wall construction, etc. I can't find a picture of it. You see them in Lowes and HD, the bathroom vanities that are only about half as deep as normal, with the big oval white sink basin sticking out way beyond the cabinet. They come as a set.

I have a friend who is mentally ill. This causes her to make some poor choices at times. Once I helped her move to a different town to get a way from a guy who had moved in on her and who she just did not have the wherewithal to say "no" to when he wanted to stay in her apartment. But they could not get along and would get into screaming fights when ever he got drunk, which was most days. This caused her to be evicted from her apartment, so I loaned her the money to move to one where he could not find her. We also changed her phone number. Well, in a fit of poor judgement, she called him. She was conned into giving him the new location. In her panic at knowing that she was going "to get in trouble" once he showed up, she took too much medicine. Then she slept too hard and woke up lying on her arm, which was numb. This did not resolve quickly, so she went into a panic. She ran water in the new vessel sink in the bathroom, trying to get her hand and arm to begin to feel again. When that did not work, she ran downstairs and outside to use her cell phone to call an ambulance (no reception upstairs in her apartment) and waited there for them to come. By the time she returned to the apartment, she had flooded the new hardwood floors in her apartment and the new drywall that was being installed in the remodeling work going on in the apartment below hers, and the water had run into the basement, two floors below! She had not shut the water off before going outside to call the ambulance!

Lesson: don't put vessel sinks in a rental unit!

Vessel sinks are the least of your friend's problems.

Sooooo, it looks like my slow draining undermount overflow-less sink isn't the the overflow-less sink's problem after all. Plumber just finished installing my husband's sink (same as mine) and it's draining perfectly. Here are the two differences. I have part of the aerator removed from my faucet. The water comes out like a garden hose therefore there is more volume of water coming out. The drain stopper in my sink is different than my husband's and doesn't lift up as far as his. So I have more water with a more restricted drain. Someday when I have nothing better to do, I'll get a new stopper assembly. It's not a big issue with me but I knew it would be for my husband. No additional drain parts (as above) were needed :)

The problem appears to be related to water surface tension with the drops spanning the small drain holes. Another option is to use a "grid" drain that has slots instead of holes. Kohler sells this unit which I installed and no longer have any problems : Kohler K-7129-VS Lavatory Grid Drain Without Overflow, Vibrant Stainless.

I LOVE that drain mwm0727! If a drain can be pretty, that one is :) I'd like to have a flat bottom surface like that in my sink. I'm guessing there is no way to stop the sink up for soaking hand washables, cleaning combs and brushes, etc.

So glad I found this thread. Two years ago I did a Vessel sink for our half bath and I was thinking it was a vent stack issues, but now it makes sense there isn't that air hole in this type of sink. i went to HD and found the parts and they have one made by Oatey

Had exactly the same issue: Vessel sink very slow in draining till a bubble came out from the grid. Followed debeall_bellsouth_net

and drilled 1/4 inch holes in all the existing 3/16 grid holes. It worked! Still not super good, but works if water tap is not opened fully. I will follow it and maybe add Watts FV-4M1 vent valve before the p-trap. Do not use the Studor AAV valve as it only admits air does not let the air from the tailpipe to escape. The Vessel sink manufacturers should tell all customers to add a vent valve in the plumbing before the P-trap.

How does a kitchen sink drain properly without an overflow?

The kitchen sink opening is so

arge that there is a clear path for air to escape from the vertical drain pipe. On the regular Washroom sinks the umbrella type drain or the grid type drains on vessel sinks there is not enough space and the surface tension doesn't allow air to escape. Does that explain?

lisa-

The overflow in a sink has one function: to handle an overflow if the water level gets too high; it has no role in relation to the drain functioning properly. Any properly installed sink drain consists of two parts: 1) the pipe from the bottom of the sink to the P-trap and then on to the sewer, and 2) the vent pipe (usually in the wall) that is connected to the drain pipe and admits air so that there is no suction effect when a large volume of water is going down the drain. If there is no vent, or if the vent gets plugged up, then the water running down the drain tends to cause a suction effect and the water drains slowly. Conversely, if a sink is properly vented, it doesn't matter whether it has an overflow or not. Does that make sense to you?

I know this is an old post but I have the same slow drain issue. Tried to implement fireman-175 fix. Got all the parts but when I tried to install my 1 1/4" tail pipe is too large to fit into the 1" compression tee. I must be missing something. Any help would be greatly appreciated. Very frustrated with this sink. Thx

rosetejas or lillo - where is the post about where to put the pin holes in please can't find anything from pliesj ...or could you be so kind as to send me photo of what you did? thank you!

I drilled 1/4 holes in my drain stainless steel grid holes and it help some. I then drilled a pin hole in my metal tail pipe under the sink like someone mentioned on here and the drainage worked perfectly. EXCEPT now the sink drips when draining into a bucket. I will replace my tailpipe today. did I drill into the wrong spot on my tailpipe?

hi - eventually I just changed the plug to a modern push down job (where the plug holes (3) are different from a traditional drain (4)) and it now drains a treat - very quick!! I'd recommend this method for all bowel sinks as you don't have to drill into pipes at all ! :-)