View Full Version : Bowl Water Level

03-16-2006, 03:53 AM
About a month ago my toliet on the first floor became plugged. I used a plunger and was able to get it flush properly. Now I notice the bowl fills up but the water level drops back down. There's still water in the bowl but not as much as before the blockage. Over time, it seems like there is less water in the bowl. I can add water into the bowl and it raises the level quite a bit. The water level in the tank is correct.
I also noticed the water level on a 2nd floor toliet is lower than usual. The bowl level never reaches it's previous height. It fills and then stops lower than before. Any ideas on what's happening?

03-16-2006, 04:01 AM
Sounds like you have a vent blockage some where. You need to call a reliable drain cleaning company.

03-16-2006, 06:06 AM
There could be several possible causes. One would be the refill tube not delivering enough water to the bowl to refill it, a second would be a vent problem, (but not likely), which is siphoning water out of the bowl. There are other possibilities, i.e., an internal crack, but without personally checking the bowl we cannot tell what the real problem is.

03-16-2006, 06:37 AM
Dumb question: are the floats both working ok?

03-16-2006, 06:44 AM
Yes, both floats appear to be working. The refill tubes in both toliets seem to be fine also. Since more than 1 toliet is having problems now, it seems like the issue is with something they share in common. As Cass suggested maybe the vent. I'm a homeowner with no practical plumbing experience so I thought I would get input from this forum to help me decide my next course of action.

03-16-2006, 07:03 AM
My guess then is that it's a vent problem.

The conventional toilet is one of the single most coolest inventions man ever made. God Bless those Romans! So simple, elegant, and ingenious!

The toilet is the only fixture with an s-trap in the house. It's designed that way so that it siphons when it gets a quick volume of water down it. That's how it flushes. Siphoning SUCKS the stuff out of yr toilet instead of just letting gravity do its thing.

The water siphons all the way out of the bowl, then the toilet starts to refill, slowly as to not cause a second siphon. Here's the relevant part: the air break via the vent between the traveling column of drain water and the refilling trap prevents the column down the drain from keeping the siphon going and from causing the trap and bowl to deplete itself of the refilled water.

So, if the water level in the tank is fine, but the bowl level does not refill completely after a flush, my guess is the vent has to be partially blocked. It doesn't let enough air in to prevent a partial siphon of the refilling bowl water. As the column travels farther down the line, the siphon is relieved, but by that time, the tank water is depleted, so you're left with a lower level in yr bowl.

Try these things to confirm: adjust the float level way up. Reflush. The extra water might be enough to refill the bowl after the siphon relieves. Then adjust the float way down. If the water level is lower than previously, then this logic might be right, and the vent has to be checked.

Incidentally, no other fixture (sink/shower) has an s-trap for precisely this reason (they have p-traps with longer horiz legs). You don't NEED siphoning in sinks/showers bkz it's mainly just water. In fact, you don't WANT their traps to siphon when you turn the water on hi bkz you'd deplete the trap of water (unless you could commit to running a slow trickle of water after each use to refill yr trap). If the vents are not sized or in proper placement near these fixtures, you could end up with a siphoning condition. Conversely, if you had a standard p-trap in a toilet, you wouldn't get siphoning, and you'd probably have a lot more clogs. BRILLIANT!!!

03-16-2006, 08:06 AM
When you raise the level in the bowl by adding water from a bucket, does it basically stay at the higher level, only going down very slowly over time?

Besides the vent issue mentioned, the only other thing I have seen do that is if there is a wad of tissue, or a washcloth! stuck in the throat, over the weir. It acts like a siphon. But this also usually either causes a very sluggish flush, or goes away after a few flushes.

03-17-2006, 03:59 PM
When I add water to the bowl, it goes down to the new lower level rather quickly. Does that help in problem determination? I can tell the level in both toliets is too low based on the ring left by the old water line that existed previously.

03-17-2006, 07:35 PM
I would say that you still have something in the toilet..........

Bob NH
03-17-2006, 08:56 PM
"When I add water to the bowl, it goes down to the new lower level rather quickly. Does that help in problem determination? I can tell the level in both toliets is too low based on the ring left by the old water line that existed previously."

One of the rules of failure analysis is that when you have a problem it is usually caused by one failure. Not always true, but that is where to start.

First, I must assume that your observation is correct, that the water in two toilets goes lower than the normal static level even when you slowly add water to the toilet bowl.

Now, what ONE failure would cause the level in two toilets to go low in a static condition resulting from gently pouring water into the bowls?

The only thing I can think of that would cause that condition is if there is low pressure (lower than the pressure inside the house) on the downstream side of BOTH toilet traps.

I assume that you don't have some great blower blowing air into your house in the winter time, and the difference in pressure due to the vent stack being warmer than the outside temperature is negligible (I calculated that to be sure.).

The only thing that could allow the pressure on the downstream side of the two toilets to be lower than atmospheric pressure is that the vent is plugged. If you are a Do-It-Yourself person, you might take a garden house with a straight nozzle up on the roof, adjust it to the most forceful jet spray, and run it down the largest vent pipe near the toilet. Push it down, with the water turned on, for maximum effect. If the vent is REALLY PLUGGED TIGHT, the pressure when the water comes to the top will almost certainly force it through. On the other hand, if the blockage is below where another vent is teed into the stack, the water could bypass and may not unplug it.

Now I have two reservations about this analysis. First, for this low pressure condition to persist after flushing, the vent must be really plugged tight. Second, something other than a blocked vent is necessary to create the lower pressure on the downstream side of the toilet. I haven't been able to figure out a reasonable scenario for that.

Is it possible that you have a pumped system of some kind, or that the municipality has some kind of pump station or vacuum collector sewer system in your neighborhood? That kind of sewer, in conjunction with a blocked vent, could cause the condition that you describe.

03-17-2006, 09:57 PM
Yup,still sounds like a vent blockage to me.

03-18-2006, 11:17 AM
I have my own septic system. I have a well along with a water softener (Model 9000 Econominder). The tank holding the salt is about 1/3 full which is when I usually add another bag. We have allot of iron in water thus the need for the softener. It seems to me that the toliets are becoming more "iron stained" since my bowl water level problem has started. Is there any correlation between the water level and staining?

03-18-2006, 04:12 PM
No, nothing that I can think of.

04-04-2006, 01:32 PM
A plumber finally came over and said I definately have a vent problem. He ran a snake from the roof vent down past my 1st floor toliet. He said there wasn't any blockages. Here's what he thought would be the next course of action. I'm interested in your input on if this makes sense and are there any other possible solution.
1) He thinks maybe the baffle in my septic tank that leads from the house might be left open. He suggests getting the tank pumped and having the baffle checked.
2) I have 2 toliets on my 2nd floor. In my attic I have a pipe that runs horizontal from the one toliet to the main vent pipe. He's suggestioning is running another pipe vertically from this pipe up thru the roof.

04-15-2006, 04:51 AM
Hi All,
Here's the latest on my situation. I had my septic tank pumped. I also removed the toliet that initially started the problem and didn't see any blockages in it.
Here's the plumber's next suggestion. Your thoughts?
I have 2 toliets on my 2nd floor. In my attic I have a pipe that runs horizontal from the one toliet to the main vent pipe. He's suggestioning is running another pipe vertically from the hoirzontal pipe up thru the roof.

04-15-2006, 07:05 AM
If the toilet was working right then started not working right, something changed.

Find what changed and you will fix the problem.

Not all plumbers are equal.

04-15-2006, 08:54 AM
Your plumber has visuals we do not! If he has good references put you faith and $$ with him. Happy Easter Tool

04-18-2006, 11:33 AM
I'm having a similar problem to TP01. I have a second floor condo unit (structure is 3 stories) with two bathrooms. One toilet is a Toto Drake and the second is an Eljer Titan. The Titan looses water after refilling more so than the Drake, and after a few day of no flushes the Titan will drop about 1.5"-2" below the static water level. Everything else is fine....both of these toilets are less than 6 months old. Anyone have a guess as to whether this would be a problem with the common pipes for the structure or does it sound like something in my pipes?

05-22-2006, 04:06 PM

I was finally able to sync up my schedule with my plumbers. He ran a new 3" vent pipe through my roof off the horizontal pipe that went between my guest bath and my main vent. I'm continue to have the same water level as before. Any ideas on what could be causing the issue?

05-22-2006, 04:37 PM
If you can see the sewer from the toilet towards the septic, look to see that it doesn't pitch up hill at some point.......

05-23-2006, 02:52 AM
Hi Plumber1,
I'm not sure I understand your post. By "sewer" do you mean my waste pipe?

05-23-2006, 07:15 AM
Sorry, I just reread your first post and my coment doesn't apply if your 2nd floor toilet reacts that way.