View Full Version : overflow tube not working on my toilets?

04-13-2007, 07:35 AM
I have a 4 yr old house with three gerber 28-790 toilets. On one of them, the fill valve keeps filling the tank intermittently even when the float raises. I assume the valve requires new washers. ANYWAY...when this happens, the tank fills until the water goes down the overflow tube, but then the tank keeps slowly filling. It seems that it fills faster then the overflow tube can get rid of the extra water. ON my upstairs bathroom, it overflowed the tank. Fortunately I discovered it before it made much of a mess. I then tested my other toilets by holding down the float to see what happens and they all overflow the tank!

Isn't the overflow tube supposed to prevent this in the event that the float or valve does not do its job?



04-13-2007, 10:27 AM
The overflow is supposed to do that, but only if the incoming water flow is not excessive, such as a dripping fill valve, not a flowing one. From your description it is not possible to tell if you need a new fill valve, bottom flapper, or both, or even something else.

04-13-2007, 12:39 PM
Actually one toilet works. Of the other two, one has a gerber fill valve and the other a flowmaster. THe flowmaster is actually worse. The flapper seems to be working fine. But if the float or valve does not work, the tank keeps slowly filling even with water running down the overflow.

The water pressure is fairly hight but does not seem too high.

I am at a loss at this point.

04-13-2007, 12:55 PM
First thing to try...pull up on the float and see if the water actually stops flowing. If it doesn't, fix or replace the filler valve. Once you get that cleared up and find it will stop, adjust the height of where the water does stop that doesn't overflow the tube. Most toilets have a mark, either printed or molded into the tank to tell you where it should be when set properly. If yours doesn't, the shoot for about 1/2" below the top of the overflow.

The procedure to adjust the fill height varies by brand and model.

04-13-2007, 01:38 PM
float and valve works (although one one toilet the valve occasionally fails which is why I discovered that overflow valve does not work). THey are adjusted so water line is right at mark on tank. It also is correct. The problem is that if I hold float down to simulate float or valve failure, the water flows until some goes down overflow. Then the water level rises slowly even with water going down overflow. IT is like it is filling faster than overflow can handle it. I think there is a problem with the toilet itself.


04-13-2007, 02:25 PM
If the valve turned off when it was full, I don't see how the bowl could overflow or the tank could. If the valves don't reliably turn off when they should, replace or repair them. If the flapper valve is leaking, the toilet will continue to run to try to fill it up, but once it reaches the proper level, it is entirely the valves job to shut off...apparently, yours isn't.

04-13-2007, 03:36 PM
Valve is working but not overflow. Everyone seems to miss the point. If you hold down your float, and watch your water rise on most toilets, the overflow will prevent the tank from overflowing. This feature is what is not working. My problem is not today...it is the day that the valve or float do not work. Instead of just having water running forever, I will have water run AND overflow the tank and do much more damage.

However, I think I may have discovered the solution. In the toilet that is working correctly, I moved the stopper to one of the malfunctioning toilets. It fixes the issue. It seems that, while all of my stoppers are of the same brand, two of them have lost their shape. They are interfering with the overflow hole which is just below the actual drain hole at he bottom of the tank.

Thanks for the help. I will follow up when I determine if new stoppers fix the issue.


04-13-2007, 07:37 PM
I replace all stoppers on my three toilets. I assume the flapper were not original on my 4 yr old house (we purchased from previous owner). The flappers all had a large bulb that was inhibiting water flow from the overflow tube. As soon as I changed to a different brand of stoppers (corky), everything is fine. THe overflow tubes now work.

I figured out the problem by studying where the overflow water passes into the lower tank. I saw that the hole it passed through was where the flapper bulb protrudes below the drain. It was keeping the water from flowing down fast enough. A simple fix but potentially a huge problem Unfortunately there was no brand name on the flappers that I removed and I did not seem them at home depot. they used a transparent rubber/plastic...not like the red or black rubber of other brands.


Reader Review
04-14-2007, 10:01 AM
Korky again.
They do make good flappers.

03-30-2011, 10:43 AM
From one person born in PA to another: borninpa, you da man!

I have four Gerber toilets --three of them experience the overflow tube blockage problem you listed. The one that doesn't is the one I replaced w/ a Korky adjustable flush length flapper.

I have two computer science degrees, so you're not going to catch me saying that my builder-installed flappers are the problem. Anything is possible. But, I'm pretty sure that the three Korky flapprs I'm about to buy will fix my problems.

Thank you for taking the time to come back and document the solution!