Water gurgle in toilet when washing machine drains

[k3pi]

Hi,

Sure would appreciate advice on this plumbing issue.

In my downstairs utility room, we have a washing machine with a toilet (and sink) a few feet away.

When the washing machine drains, the water in the toilet bowl will gurgle (you can see the water move and slosh around in the bowl) and usually most of the water will drain out of the toilet bowl by the time the washing machine finishes draining.

If you try make the mistake of flushing the toilet while the washing machine drains, the water in the bowl rises to the top and comes close to overflowing.

Additional hints:

This washing machine-toilet thing has been going on for quite a while.

We have never had any back up in the washing machine drain.

We recently had our drain pipe (from kitchen to the main drain) power-snaked out because draining water from the kitchen was backing up into the kitchen sink. The kitchen sink problem was a new one. This has corrected this problem. If I understood the plumber right, the power-snaking went beyond the length of this particular drain line and into the main house drain pipe. (The kitchen is "ahead" of the utility room about probably 30-40 feet away).

The upstairs toilets don't seem to be affected by the washing machine draining.

Your advice on how to go about fixing this is really appreciated!

Thanks Russ

[barry]

Hi, Russ.

Improper/inadequate venting.

HTH, J

[Speedy Jim]

While venting may be a part of the problem, I don't think it answers everything.

It sounds more like there is a restriction (blockage) in the line serving both toilet and washer. As the water backs up, it forces air and water up to the toilet connection. Then, as it does drain out, siphoning occurs from the toilet bowl.

For a quick test, pull the toilet up and watch what happens in the sewer line below as the washer drains.

Or...do the "bucket test" on the toilet. Line up a dozen buckets of water. Rapidly dump them into the toilet. If there is no blockage, the water should go down as fast as you can pour.

If the sewer is buried under a slab, it is not unusual for tree roots to penetrate far under the slab where they can create a blockage affecting only part of the house (just one theory).

Well, those are some tests I would do before making a project out of it.

Jim

[k3pi]

Thanks for the replies.

Speedy Jim, can I ask a couple of follow up questions. And I apologize in advance if they are "dense"

There probably isn't a "typical" connection but what I am envisioning is something like one of these 2 scenarios, since it seems pretty obvious that the washer and toilet share the same line:

Washer Toilet X X X X X X X X XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX (Shared line) XX XX XX XX XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX (main drain line)

Washer Toilet X X X X X X X X X X X X XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX (shared line) XX XX XX XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX (main drain line)

1) One thought I had was that the discharge from the washer might be fully occupying the shared line between the washer and the main line, giving the toilet discharge nowhere to go. Is this a bad assumption?

2) Are you thinking that there may be an obstruction in the what I am showing as the vertical connection between the shared line and the main line? Not big enough to prevent the toilet from flushing "on it's own" but enough to prevent the washer from freely draining and looking for another place to go?

3) If the answer to 2 is yes, would I not get backing up in the toilet (non-flushing). I am not getting bubbling in the toilet, which I thought I might see if there was air coming back (only a gurgling noise with gradually lowering water level in the bowl). The toilet bowl water does not rise (non-flushing), which I guess I would assume would accompany drain water backing up. Or is the sloshing indicitive of both water and air being forced into the toilet.

I appreciate your patience with these questions. Please correct me where I am off track. I hope these "diagrams" come through ok.

Speedy Jim wrote:

[Speedy Jim]

Diagrams Ok.

Could be like #2, or even the reverse of that. The sloshing indicates air pressure in the line because the washer water is filling the line.

As the other gentleman suggested, a vent would relieve that but I'm suspicious that something else is going on. Really hard to guess from afar without seeing the layout though.

Particularly troublesome is the fact that the toilet won't drain if the washer is draining. A vent has no bearing on that.

Play detective and do whatever snooping and testing it takes. Jim

[Tom The Great]

Wow the subject alone was enough info. I would see about having a 'real' plumber check your system, you might have a venting problem. The plumber can see if you have an underdesigned system, or maybe something fell into your vent stack.

Good luck, fill us in on what you did later,

tom @