Toilet water level low

[Sam_RN]

Bought a house built (poorly) in the 90's. In the master bath, which is on a concrete slab foundation, the toilet has given me issues since moving in. It's an old Proflow 1.2 gal/flush model that was probably the cheap contractor special at the time.

Symptoms:
- 50% of the time, after flushing, over the next 10 minutes the water level in the bowl creeps lower and lower until some bubbles appear.
- The other 50% of time, the water level remains normal after flushing.
- Sometimes, if the water level is normal, and I turn the sink on in the bathroom, the water will then decrease in the toilet bowl.
- Toilet suffers from very weak flushes and takes two or three flushes most of the time with holding the lever down for several seconds in order for matter to leave the bowl.
- When toilet is flushed, a loud gurgling noise can be heard down the hall from the drain opening in the wall that the washing machine dumps into.

What I've tried:
- Replaced almost all internal toilet components that can be replaced.
- Uninstalled toilet, replaced ring with new, updated one, and then re-installed.
- Snaked 25 feet in from toilet
- Snaked 25 feet in from roof vent serving this toilet. The whole house is a single-story.
- Installed air admittance valves under the sinks in this bathroom and the kitchen (the kitchen sink is just on the other side of the wall from this bathroom and the one vent serves both).

What has helped:
- Nothing. The roof vent was clear, as was the toilet trap and pipes downstream. When we moved in, we had a plumber snake out from the clear-out to the sewer connection and it was all fine.
- I have snaked the vent from the roof twice annually and each time there is a small amount of leaves in there but even after clearing the vent completely, it has the same issue.

What plumbers have told me:
- One plumber told me that he'd "bet a week's pay" that my problem is the toilet. He said there might be a tiny burr in it that solid matter gets occasionally caught on and wicks the water out of the bowl. He said that he thought if I replaced with a new toilet, that would solve my problem.
- Another plumber told me that the problem was with the venting, so that's why he installed AAVs. That didn't help.
- A third plumber told me that the venting was likely at fault but that the only solution would be to literally demolish the bathroom, rip out the wall behind the toilet, remove the tile floor, break up the concrete foundation, and re-plumb everything.

I am looking for some advice. I'm more than happy to buy a good Toto toilet and install it if people here think that might help me out in this situation.

Here's a video of a particularly problematic flush:

I really appreciate it!

 

[Reach4]

- Installed air admittance valves under the sinks in this bathroom and the kitchen

While venting is unlikely to be the cause, as a test, remove an AAV, and see if the flush improves. Ignore any temporary smell.

One plumber told me that he'd "bet a week's pay" that my problem is the toilet. He said there might be a tiny burr in it that solid matter gets occasionally caught on and wicks the water out of the bowl. He said that he thought if I replaced with a new toilet, that would solve my problem.

Take the bet , but for a lesser amount, and lose. It will be worth it to have a good flushing toilet.

 

[Sponsor]

 

[Terry]

I would be inclined to change out the toilet. I would maybe bet a cup of coffee. Not a weeks pay. I don't mind buying coffee.
Adding AAV's to what you have would have helped on venting. You did that.
You've snaked the line.
Sometimes there is something in the trapway wicking. And for a good flush, the bowl must start with enough water so that added water starts a siphon. With your bowl and no water there, it's really hard to start that siphon action.

 

[Sam_RN]

Alrighty, sounds like I'll be changing out the toilet. Thanks guys. I'll update if that doesn't fix the problem.

 

[Sam_RN]

Update: I went ahead and installed a Toto Drake II today. I also went on the roof and put a 25' snake thru the vent and also poured Drano in the vent and then flushed it out with hot water. The flush on the Drake is WAY better than my old toilet, but it still bubbles a lot at the beginning of the flush. Then after the flush is finished, the water level in the bowl is slowly sucked to a lower and lower water level until there is only a small amount of water left in the bowl.

I confirmed that I was able to hear bubbling/gurgling and flush sounds from the roof vent while listening from the roof when my wife flushed the toilet.

I'm at a frustrating loss.
Any ideas what this vent problem might be? What would make the water suck back in after flushing?

Thanks

 

[Terry]

That sounds like the venting isn't happening for that toilet line. The vent breaks the siphon. Sorry. Not what I was expecting.
I would have expected that the AAV on the lav would have helped that.

It's possible that the main line to the sewer needs to be cleared. You went out 25 feet last time?
Before you break anything up, I would pull the bowl and bring somebody in with a proper sewer snaking machine and really make sure that line is open and clear. The AAV on the lav should have been enough.

 

[Reach4]

I'm at a frustrating loss.
Any ideas what this vent problem might be? What would make the water suck back in after flushing?

Remove the near AAV, and see if the flush improves. Ignore any temporary smell.

 

[Sam_RN]

Terry, you say the AAV should have worked but Reach4 is saying the opposite? Or am I reading your responses wrong?

This new toilets flush is almost worse than the old one now. It’s all because of the vent issue though. I am so pissed too because of course this toilet is set in a concrete slab of unknown depth. Is there a straightforward way to somehow install a new vent on this toilet without having to bust up the tile floor and concrete foundation?

 

[Terry]

I'm thinking more that it's a main line backup and the venting is fine

 

[Sam_RN]

If it were a main line backup, wouldn’t I expect other drains to be slow as well? It’s a 1000sqft single story home, no problems on any other drains (including the bathtub and sink drains in the same bath OR the toilet in the second bath).

I am really hoping it is just a backup because that would be way easier to fix than venting. Should I remove the toilet and try another snake to clear it out?

 

[Terry]

Has any of those plumbers put a camera down the line? It sounds like every one of them tried to find a good solution. If a camera finds what we can't guess, then maybe it shows us a better way to a solution.
A true main line back up would show at other fixtures, especially the tub.

 

[Sam_RN]

Nope, three plumbers out and none of them put a camera in the line. That will be my next step I believe at this point. Thanks for the help.

 

[Reach4]

Terry, you say the AAV should have worked but Reach4 is saying the opposite? Or am I reading your responses wrong?

An AAV can prevent a vacuum, but it cannot release a pressure. Removing the AAV as a test may let the toilet flush nicely. If might not help the flushing. If it does not help, to me that would tend to point to a drainage problem rather than a venting problem.

Even if it helps, it could be a drainage problem. There could be a belly in the drain line stopping air flow.

 

[aquatekuk]

The AAV should be the problem here if that doesnt work then it will be a drainage problem surely!

 

[Sam_RN]

I wanted to update because I know you guys are probably on pins and needles wondering what the issue here was. I hired a small independently owned drain cleaning company to come out and put cameras all through the plumbing to see what the issue was. It turns out is WAS a venting problem but it was due to a belly in the line. Here's the write-up from the inspection:

"Used camera to verify toilet is clear as well as the sewer line. Inspected from the toilet and from the roof vent to verify vent is clear. Unable to advance too far from roof vent due to number of turns in line. There is a deep belly in the sewer line from just below the toilet out to just beyond the outside foundation wall. The pipe is completely under water at the tee into the main just below the toilet. The stand pipe at the toilet flange goes straight down into the main. Since this section of main line where the toilet connects in is just below the toilet and this section is under water, the toilet can't properly vent. The apex of the belly is likely at least 3 ft in from the outside wall, but may be in as far as below the toilet. Impossible to tell for sure. Located line in a few spots outside as well to determine depth of line in case line needs to be connected farther out to get proper grade. Line is functioning now, but is more susceptible to clogging."

According to him, the next step would be to contact plumbers. My hope is that we can figure out a way to just tear out the shower in order to gain access to enough of the belly in the drain line to re-slope it as it exits the house. I'm going to try to minimize how much of the concrete foundation needs to be ripped up in order to fix the problem.

It isn't an urgent issue, but certainly something I'd like to not have to live with for the next 5 or so years while I'm in the house. Also would be worried about the next buyer's inspection turning this problem up and us having to fix it prior to selling.

Not great news but also not the worst it could be! If we can fix the belly with all the standing water, hopefully the vent will work as intended .

 

[Terry]

Thanks for the update. That makes sense that the belly is the problem, and more ways than one.

 

[Jadnashua]

Well, you could call it a venting issue, but if the main line is not draining, no amount of venting will help! As long as air can get into the system, gravity should let the waste flow out. Bad venting could cause a trap to be sucked dry.