toilet bowl water level near empty

[ckim]

Initially, I had a toilet that didn't seem to flush completely. When I went back to check the toilet has very little water in the bowl. The tank and the mechanics all seem to be working fine. When I flush, the toilet bowl fills with water filling it near the very top (almost looks like it will overflow) but it slowly works it's way down. And at the very end, the toilet bowl is near empty ending the flush with hardly any water left. The tank seems fine. I'm not sure what a vent pipe is (on the roof) as I was reading other posts and they seem to direct people to check that. Any suggestions [?] are greatly appreciated! [:I] Thanks kim!

[LazyPup]

Low water level is a prime indicator of an obstructed vent. To locate the vent look on the roof of the house directly above the bathroom area, you should see a 3 or 4 inch diameter pipe sticking up through the roof about two feet. If you have a basement go down and look for the wetvent stack directly below the vent pipe on the roof. There should be a cleanout cap on the base of the vent stack where it meets the building drain. You can either snake up from the bottom or if your on a slab it is easier to snake from the top down.

[ckim]

I live on a slab and I've never ventured on the roof of my house. Once I locate the 3-4 inch pipe, do I just use a "snake" and run it down? How does a pipe on the roof interface with the plumbing? And is this "snake" the same kind that I would use to clear a pipe obstruction?

Thanks for your help!!

[kactuskid]

"What is the purpose of the roof vent?
All houses have plumbing vents (also called a vent stack) that extend through the roof. These vents allow air to flow both in and out of the house plumbing system, helping water to flow through the pipes. Working in combination with the vapor traps, gases from the sewer system are safely vented."

You could have either a birds nest, leaves or anything else clogging your main vent stack, so yes, use a regular snake that you would use to clear an obstruction down your vent stack. If this dosn't do the trick then you have a clog in your drain piping and you should then pull your toilet and again use your snake to try and clear it.

[ckim]

Thanks. I am going to have to go out and buy a snake. Hopefully it will be fairly obvious if there is a clog. Otherwise, I think if I have to remove the toilet and run a snake down the main pipe, I would rather call a professional.

[dlikens]

I've had a problems like this also. But, it happens to the 2nd floor toilet and happens mostly on windy days.

[LazyPup]

Ckim..
To answer your question about how the main vent interfaces with your building drain system, i would like you to try a simple experiment. Take an ordinary soda straw and insert it into a glass of liquid. Now cover the top of the straw with your finger and lift the straw out of the glass. Notice that the liquid in the straw remains in the straw as you draw the straw out of the glass. Now remove your finger from the top of the straw, and instantly the liquid falls out.

Basically the same thing happens in your drainage pipes. If the vents are open, allowing an ample supply of air to enter the drainage system, the liquids and suspended solids will flow. If a vent is only partially clogged the velocity of the flow is lowered. As the motion of the waste is slowed there is no longer sufficient force to carry the solids, which now sink to the lower part of the pipe and the liquid slowly seeps past. Once the liquid has passed the solids are now exposed to air and they begin to dry into a hard lump. Each successive use of that drain line will deposit even more solids until the line is totally obstructed.

To the uninformed it might appear that plumbers place way too much emphasis on the vent, but in truth, the vents perform three distinct and vitally important roles in your plumbing system.

1. Vents insure an adequate supply of air to insure proper velocity of flow.
2. Vent obnoxious odors and potentially harmful gasses into the atmosphere.

The third function of the vent is a bit more complex to understand. Years ago all houses had a huge trap on the main drain line immediately outside the foundation of the house. The purpose was to prevent the sewer gasses in the municipal lines from getting into your house. In those days both the sewer and storm drainage ran through the same municipal lines and often emptied directly into rivers or streams. In those days the the sewer gasses vented through the little holes in manhole covers or through storm grates. As the municipalities began building sewage treatment plants it was soon realized that allowing storm runoff to enter the sewers overloaded the treatment plants so they then put in separte sewer lines for the storm runoff. The problem was that once the storm drains were attached to a separate line, the sewers no longer had the storm grates for vents and the gasses built up to very dangerous levels in the sewer systems. The end result was that many municipal sewer workers were asphyxiated and in some instances the levels of methane gas were so great that sewer lines actually blew up, causing serious property damage and in some cases even deaths occurred.

To alleviate the problem the plumbing codes were changed. No longer were house traps permitted. In addition, it was determined that there must be a minimum of a 4 inch diameter line from the municipal sewer to the house. The lines inside the house were now sized by the number of drainage fixtures attached to the line. The main drain running under your house may be either a 3 or 4 inch line.

The code also states that at least one vent must be connected to the main drain and run up through the roof of the house, undiminished in size. Thus, the main vent not only allows adequate air into your drains and vents the sewer gasses out of your house, it is also an intergral part of the venting system for the entire municipal sewage system.

The codes are also very specific about the length that a line may run from a vent, by example,The International Residential Plumbing Code states that an 1 1/4 inch drain line such as is attached to your bathroom sink may only run 5 feet from the trap under the sink to the point were it connects to the vent. (Only 2.5 feet under the Uniform Plumbing Code).

There are very complex tables in the plumbing codes to determine the required diameters and lengths of drain lines. When it is necessary to run a greater length we either have to use a large diameter line, or install an auxillary vent to serve the fixture.

CLEANING DRAIN, WASTE AND VENT LINES:
Normally the small diameter snakes found in hardware stores or home centers are only effective on lines up to about 1 1/2 inches in diameter.

Cleaning DWV (Drain, waste, Vent) lines greater than 2 inches normally requires a heavier powered auger system with the appropriate cutter to match the line diameter.

The type of machines required to clean 2 inch or greater lines are relatively expensive, starting at about $600 and up.

The machines can be rented quite reasonably from local tool rental companies or sometimes from the larger home centers such as Lowes or Home Depot.

They are not difficult to operate, but the machines are very heavy and it is a very messy job to say the least.

To use the machine you insert the cable with a cutter head into the line through a cleanout fitting then turn the machine on and continue feeding the cable into the line.

You can lift a toilet and use the toilet line as a cleanout access, or you will find a cleanout fitting attached to the main vent were it meets the building drain and their is a main cleanout at the point were the building drain meets the building sewer. (If the house is on a slab the main cleanout is about 3 feet outside the building. If you have a basement the main cleanout will be near the point were the building drain passes through the basement wall.)

The Code also requires a cleanout be installed on each line at any point where it makes a 45 degree or greater change in direction.

Although it is a bit difficult to do, a powered auger may be fed down from the top of the vent stack.