View Full Version : Lavatory Drain NOT Draining

12-23-2005, 04:08 PM
I have recently installed two new lavatory sinks, small bowls...11", with no overflow. I also installed a grid no overflow drain to go along with it, now the problem is that the sinks don't drain as they should, they drain slow. At first I thought something was clogged so I rodded everything out..... ALL drain lines, stacks... everything but still no luck, so I got a cheap drain from HD with a stopper and stuck it in, without the stopper, and the sink drained just fine but this isn't the drain that I want to use. I thought that the grid holes were to small, so I got another grid drain from Kohler and still no luck..... So I figured it has something to do with air equalizing or something like that. I guess my question is what can I do to make the sinks work properly, with still using a grid drain? Any help would be greatly appreciated!

Rob :mad:

12-23-2005, 06:07 PM
Why would you buy sinks without overflows?
Overflows actually give air to the drain and help the fixture to drain better.

12-23-2005, 06:12 PM
I was looking for a specific size and that is all that I found, now that I know what I know I shouldn't have over looked the overflow... when I bought it I didn't think it made a differenece, but I know better now. Is there something I can do to fix the current situation?

12-23-2005, 06:27 PM
Grid drains shouldn't be the problem.

Who did the roughin for the lavs?

Does the plumbing in the wall have vents?

(Dec 24th update)
Reading the other plumbers comments, it does seem that a lav with an overflow would have drained well. That's the only way I've installed them.

I'll remember that bit of informaton when a customer wants a lav without the overflow and a grid drain.

12-23-2005, 06:34 PM
Its an older building, so I don't know who did the rough in. But I do know that they are connected to the stacks.

Why would the sinks drain fine when I put in a regular drain vs a grid drain? I figured that the regular drain let water drain faster and it never covered the top of the drain so air could get by....

Not sure what to do from here????


12-24-2005, 05:56 AM
What you figured was probably correct.

Is this a commercial building?

I've seen that same thing with those same grids.

Can you find p. o. plugs that only have a + at the opening?

It's a (cross) that prevents objects from going down the drain.

I'm sure that would be better.

Been there and done that.

Cheaper isn't always better. Sometimes it's more expensive....

12-24-2005, 06:53 AM
The grid strainers, along with no overflow is the problem. If the water were running slow enough that the air caught between the grid and the trap could escape fast enough, then it would drain properly. But, unfortunately, the water covers the grid and the air cannot escape through the small holes as long as the water is also trying to flow through them. Use a drill to make bigger holes and the problem will be solved. Just keep trying larger sizes until you reach the point where the drain flows properly.

12-24-2005, 07:02 AM
You can test this by placing a straw in one of the holes and turning on the water. Water will fly down the drain.

12-24-2005, 08:11 AM
When I drill the holes larger, won't that mess up the chrome on the drain? How can I prevent that ?


12-24-2005, 08:39 AM
You can't...the chrome will fail. Sounds like you need a different style.

12-24-2005, 08:57 AM
I installed the gird drain by Mountain, MT740, I also tried a Kohler model as well. The Mountain seemed to work a bit better, I saw a different Mountain model, MT749, its a tear Drop style. I was wondering if anyone has ever used that drain or think it would work better.... or knew of any other "grid" style drains with larger opening???

Thanks for all the help guys... I was really puzzled by this problem till I found this site!



12-24-2005, 06:50 PM
If you can find one with a "beehive" dome shape, it will probably work better.