Removal of backflow preventer flapper

Hi,

I've posted in this forum before about an ongoing backup problem that's been happening in my house....going on 3 years now. Basically, on an intermittent basis, while taking a shower or washing clothes, the toilets gurgle, get siphoned of most of the water in the bowl, and then the main drain line in my house backs up into the laundry room (the lowest point in the house).

I've had numerous plumbers run a camera, I've had the vent pipes replaced from a 1 1/2 in to 2 in, and no one can come up with a definitive answer that someone else will back up.

My builder is involved and will be dealing with this until it gets fixed, and yes I have it in writing.

They sent out an expert last Friday, who is convinced that the backflow preventer flapper in the cleanout is causing the problem....that toilet paper is getting caught on it. The plumber wanted to take the flapper off, but it's code here in my city that there be a backflow preventer. After the builder talked to the city sewer dept and found that it can be taken off, but the city won't be held responsible, the builder gave the ok to the plumber to take it off. (I have a letter from the builder saying they will take responsibility if something were to happen as a result of the flapper being off.)

So right now, it's a waiting game, to see if the backups happen anymore.

Another piece of background info....a plumber I hired about 6 months or so ago, says that my whole main line has inadequate fall. He put a camera into the line, from the cleanout into the house, instead of from the toilet to the cleanout. When running the shower and flushing the toilet, the whole main line fills up with water and is slow to drain. However, when the camera is run from the toilet to the cleanout, you don't see the same thing. So, that's causing me some confusion.

So, here are my questions:

1. Can a backflow preventer flapper be the cause of this 3 year headache?
2. If so, is taking it off just merely a bandaid, meaning there is a bigger problem than that?
3. Is there a way to measure the pitch of the main drainline in the house, without tearing up the floor? I'm on a slab.
4. Can running the camera from the outside in show something different than running it from the inside out?


Thanks for any answers you can provide.

The drain line could have a belly (dip) in it...water doesn't like to flow uphill and depending on what is there caught in that belly, clog things up, then when you get enough flow, it washes it out. Or, it could have a section that is flat with no slope at all or barely any slope.

You may be able to ask the city what the depth of the sewer connection is at the street. Then, you'd need to figure out the depth of the exit point at the house. Then, measure the distance between those two points. Ideally, you've got 1/4" per foot or more. Depending on the diameter of the pipe, you might get by with slightly less. My guess is a good operator would be able to make an assessment on the slope, but I have no experience with scoping drain lines.

Thank you for your reply, Jim.

As for a belly being somewhere in the line, I guess it depends on who you ask. I've had one plumber say there is backfall....two plumbers say the line has inadequate pitch....and several other plumbers say there's no problem at all.

I'm not sure what the diameter of the pipe is, but I do know that it should have 1/4" per foot pitch.

It's very frustrating!

cmc said:

Thank you for your reply, Jim.

As for a belly being somewhere in the line, I guess it depends on who you ask. I've had one plumber say there is backfall....two plumbers say the line has inadequate pitch....and several other plumbers say there's no problem at all.

I'm not sure what the diameter of the pipe is, but I do know that it should have 1/4" per foot pitch.

It's very frustrating!

Click to expand...

The proper flow should end up being close to 2' per second.
Which is a good clip.Any faster and your water runs away from your solids
and that ,of course,will cause a problem too.
Run with this:

Size of Piping Minimum Slope

Less than 3 inches 1/4 inch per foot
3 inches to 6 inches 1/8 inch per foot
8 inches and over 1/16 inch per foot

Other thing..is it vented correctly?
is there some sort of vent after the check?
Could the check be heavy enough to choke off any needed venting.
A Gurgling toilet is bad venting or
A line backing up. Good luck on this dilemma.

It is hard to say what the problem is with the camera going reverse to the flow unless the operator had something on the camera head to hold it off the bottom of the pipe. On many cameras the lense would only be a half inch or so off the bottom of the pipe. With water running against it the bow wave would certainly put the lense under water. If the other camera inspection showed no water holding in the line all the way to the street I would say chances are it is not a pitch issue.

Backwater valves do have maint. requirements and IMHO make a line less reliable. Access is required for cleaning. How is yours as far as access and do you know how to clean it?

As far as the clog... Do you know where the clogging is occurring? Is it at the backwater valve? Is it in the line somewhere? The drain cleaner needs to give you an indication of where the problem is! How are they clearing the clog?

slow drain

why dont you flush the toilet and see how long it
takes to pass the cleanout in the font yard???

if you flush it and it never seems to pass the clean out pipe
then you got troubles in the slab...cause it is filling up the line instead of rushing out of the system like it shoud
that is a bad situation


back flow preventers are a joke anyway ...unless you are in an area that has proven back ups throughout the nieghborhood they are really not necessary...

Any water left in a pipe, after enough time has elapsed for it to drain out, indicates the is a problem with the pitch of the line or a stoppage causing it to back up.

If a camera shows a line with standing water in it that is the first thing that needs to be addressed. Once the backed up water problem is corrected then you can look else where for another problem if the initial problem persists. There should never be standing water in a drain.

One thing you can do, which should have been the first thing done, is when the house backs up look in the C/O and see if there is standing water in it.

If there is the problem is between the C/O and the street. Were not talking rocket science here.

It is possible you have 2 problems.