Latest Discussions : Plumbing


10:41AM | 06/26/05
Member Since: 06/25/05
3 lifetime posts
I have a Mansfield 1.6ga elongated toilet. Problem I am having is the water level in the bowl gradually drops to just below the water flow hole at the bottom ot the bowl.

No water is leaking from the tank and no water is leaking around the bowl. Why would the water level in the bowl drop. I have another bathroom connected to the same drain less than 6 feet away and it does no do this. Thanks for your assistance.


05:59PM | 06/26/05
Member Since: 01/28/03
693 lifetime posts
Could be your toilets or other fixtures are not vented adequately and the other toilet or other fixtures is drawing air from this one.

Could also be a hairline crack in the bowl which is leaking into the waste pipe unnoticeably.


04:53PM | 06/27/05
Member Since: 06/25/05
3 lifetime posts
I have not checked the vents yet, would the vent cause the water level to still be drawn down when other fixtures are not in use? Also, the toilet is secure and has not been snaked or hit, so I don't think a crack is likely, Possible but not probable.

It has been in place for approx 5 yrs and this problem started about 2 weeks ago.

Thank You for you assistance.


04:34AM | 06/29/05
Member Since: 01/28/03
693 lifetime posts
Blocked or improperly installed ventilation can cause water levels to drop when other fixtures are used.

It is not unusual at all for toilet bowls to crack suddenly and without reason due simply to manufacturing defects or stress (like someone standing on the fixture).


05:15AM | 06/30/05
Member Since: 08/29/04
227 lifetime posts
Absolutely right. If you flush a toilet in a basement, and you have a blocked vent, it will try to draw air from an upstairs fixture. The funny thing about air, is it has volume. So if you put water into a system (which has weight) it will push the air ahead of it, leaving a vacuum behind it. The missing air has to be replaced. With a blocked vent (often a birds nest or dead animal) your system will not function properly.

Raymond VinZant Plumbing Prof.


08:01AM | 07/04/05
Member Since: 06/25/05
3 lifetime posts
Since the bowl was flushing properly I did not snake it. Well, for the sake of elimination, I snaked it and out came small peice of guaze, (like bandage guaze) it was not not very big and I don't know where it had lodged, but after it came out, the bowl did not siphon down. It has worked properly since.

Thank you folks for responding, I now know where to go for help for all my home questions.


03:50AM | 01/31/15
Member Since: 01/31/15
2 lifetime posts
Would a clog in the vent pipe cause the water levels in the toilet bowls to drop when the house is NOT being used at all? All four toilets fill normally when we are at our vacation house. We do not notice any low water levels even if we are there a week. Then the house is empty for 2-4 weeks, and when we return the toilet bowl levels in all the toilets in the house are low! This is a new problem that started several months ago and is getting worse. All four toilets on two floors are affected.

There are no visible cracks or leaks in the toilets themselves.
Could it be something other than the vent pipe?


06:44PM | 01/31/15
I'm having the same problem. Bowl flushes fine but water level drops. I can hear trickling from down low (well below the tank). Flushed the roof vent. Used a drain auger and nothing came up. No other drains having issues.

Next step is a new toilet??


06:58PM | 02/01/15
Sylvan posted

A trap seal (toilet for example) can lose its seal from

Negative pressure, (down drafts for example) positive pressure,capillary attraction, evaporation, osculation << wind effects

A blocked main vent terminal would not just cause the problem when your away


12:09AM | 10/16/15
I've noticed the level drops in our lesser used toilet after a pretty windy day, so I think the downdrafts/ wind effects answer is spot on


02:44PM | 02/15/18
I have two bathrooms, back to back, same fixtures exact installation locations, just on opposite side of wall. One bowl, flushes ok, tank refills ok, but bowl level slowly drops. Poured 1-2 qt water into bowl, without flushing, and that level stays,(at normal) But if we flush again, bowl water rises to lid, then drains, leaving a lower that normal level. Been going on for a few days, now the other toilet is doing the same. Could under the slab roots be the problem, cracked pipe? Checked the vent pipe, no problem there. Any ideas.


03:58PM | 08/16/19
6-8 week problem. A toilet used occasionally during the day functions normally. The toilet bowl flushed in the evening (last flush of the day) fills normally with water and is not used overnight. Next morning the bowl water level has dropped noticeably and the toilet gurgles when first flushed. The water level in the bowl returns to normal after the first flush. There is no water on the bathroom floor or in the crawl space under the toilet. A video snake beyond the inverted "U" shows no retained material that would act as a siphon and no porcelain/ceramic micro-fracture could be identified. Vent is shared by kitchen and laundry room where no problem is evident. Is a new toilet the solution?


09:09PM | 03/06/20
Is it possible a wick effect is dropping the level like something you cant see in the toilet trap ? Is it possible for a toilet a story above this toilet to have too small a air vent and its putting a vacuum on the lower toilet as water passes by ?


12:39PM | 06/28/20
Is there any toilet on the market that will not release sewer gas whether it's cracked or leaking?


12:44PM | 06/28/20
Which toilet bidet combo do you recommend? Or do you recommend a separate bidet feature?


10:46AM | 09/05/20
Toilet was not flushing well. I cleared the air vent and now seems to flush better, however, the toilet bowl water level and toilet tank level drops. Can't just be the flapper valve, otherwise it would just be the tank level going down. I've snaked out the toilet and doesn't appear to be anything siphoning it. I've changed the filler valve, no change. The only thing left is to remove the toilet and look for cracks. Will I see a crack? If I reused the old wax seal will that cause an issue? - I don't see how it could drain. I have a vent which I cleared and an air admittance valve (cheater valve) under the kitchen sink. I removed the air admittance valve and flushed the toilet, the toilet still drained so that rules out a blocked air vent. What's left is something siphoning the snake couldn't get or a hairline crack, maybe the wax seal??
Any help would be appreciated.
About to remove the toilet to check.


09:52AM | 09/18/20
The rubber gasket between tank and bowl could be letting air in.


09:53AM | 09/18/20
The rubber gasket between tank and bowl may be letting air in.


06:49PM | 02/15/21
Toilet continues to siphon water just enough to result in a low level in the bowl. Could it be the filler valve as it leaks when filling. The over flow tube is getting plenty of water while the tank is filling. I hear the siphoning at the end of the flush.


03:06PM | 03/20/21
No water in the toilet bowl goes down about a quarter of an inch after each flush I removed the toilet, put it up on blocks and poured water in the bowl. Water is dripping out drain could I have a crack somewhere


03:17PM | 03/20/21
No water in the toilet bowl goes down about a quarter of an inch after each flush I removed the toilet, put it up on blocks and poured water in the bowl. Water is dripping out drain could I have a crack somewhere

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