Toilets bubbling when showers drain

Plumbing Forums

Help Support Plumbing Forums:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

Gatorfreak

New Member
Joined
May 6, 2010
Messages
2
Reaction score
0
Location
,
Bathrooms are on opposite ends of the house. Every now and then, both toilets will bubble/gurgle/splash when a bath tub is draining. Happens from either tub/shower draining.

Yesterday, this happened and the bathroom on the opposite end of the house from the draining tub had a bad sewer drain pipe smell right after.

I'm stumped as to what could cause such behavior. FYI - I'm on city sewer/water.
 
Bathrooms are on opposite ends of the house. Every now and then, both toilets will bubble/gurgle/splash when a bath tub is draining. Happens from either tub/shower draining.

Yesterday, this happened and the bathroom on the opposite end of the house from the draining tub had a bad sewer drain pipe smell right after.

I'm stumped as to what could cause such behavior. FYI - I'm on city sewer/water.


This is an indication that your Drainage has a `Fault`- sounds obvious - BUT this could be hard to `pin down` over this Forum - there will be many theory`s - as what you describe is caused by a Fault / Blockage [possibly partial blockage] that is causing `Negative Pressure` in your Drainage System.
NORMALLY we would be `diagnosing` that the `Venting` on your above ground drainage was `incorrect`- BUT you have stated that the `Toilets` are on opposite ends of the house - so it is very unlikely that you have all the `Toilets` and Baths etc. connected into the same above ground drainage - In the U.K. [where I am] - we call this - Soil Stack for W.C. [Toilet] Drainage and other waste water - OR Waste Water Stack for water only [+ condensate - if PVC] .

What does `Link` all your W.C. [Toilet] Drainage and All the Waste Water Drainage - including your Baths is the MAIN DRAIN RUN from your property - AND it `seems` that there `must be` an issue with `VENTING` that MAIN DRAIN RUN [?]

This is just ONE of the `Theories` that you will get regarding your `problem`-
You MAY have a `partial blockage` in a section of your main drain run - which does allow Water and some solids to pass - this could be `far enough` away from your property that no `back - up ` has reached the bathrooms etc - YET.

When you empty a Bath or have a `long` Shower- the Volume of water discharging into the DRAIN RUN and filling it up quicker than the `partial blockage` will allow the water to Drain away - causes a `Positive Pressure` - which has the W.C.`s [Toilets] to `Gurgle` - THEN as the Volume of water passes the `Partial Blockage` - a situation arises where a section of the Drain Run is FULL of water and is NOW `sucking` [Negative Pressure] the water out of the Bath Trap [and others?] - allowing the `Smell` and `Germs` from the Drainage System to enter your home.

Although the `Smell` is `distasteful` - these `Fumes` are Dangerous to your Health - Germs are coming into your property - VIA the `siphoned` Bath [and other] Trap which when empty - is the end of a direct pipe to the Sewers !!
You should Run a Bath Tap [Faucet] after you Drain the Bath - to FILL UP the trap again [ as a temporary measure] - which will `re-establish` the SEAL - and eliminate the `exit` of the `Smell`/ `Unhealthy Gases`.

What I have described can [usually] only happen when there is an `existing problem` with the `VENTING` of the DRAINAGE SYSTEM - and then a `Partial Blockage` occurs - EVEN THEN - the circumstances have to be `just right` - to cause the Problem that you seem to have.

It is not be possible to be SURE that this is DEFINITELY what is happening at your property - BUT I would recommend that you TRY to `check` your Drain Run - If you have Inspection Chambers / `Clean outs` ? - try to check using a FULL BATH of water -each time- IF the water is flowing away as fast - down the Drain Run - as it should be ? - Also note any `effect` that you notice on the `Traps` of Sinks, Baths, Basins, Bidets etc. - you already know that the `Gurgling` of the Toilets is happening - CHECK that this seems to be Air emitting FROM the Toilets ? - not a `Sucking` effect ? [Siphoning].
Although EITHER is indicating `Pressures` which should NOT be occurring in your Drainage/ Waste Water System - it might be `useful` to know WHICH is happening.[?]

The `issue` with the VENTING of the Drainage is that: the situation that I have described - SHOULD NOT BE ABLE TO HAPPEN.
The Drainage Runs should have `Stacks`/ Vent Pipes connected to them which would allow `Air Behind Water` - to prevent `Negative` and `Positive` Pressure Situations of the kind that I have described.

I await - `with interest`- the comments of the other `Professional Plumbers` regarding my descriptions here .
And of course there will be other `Theories` some of which may be just as `Valid` as this and some that may identify your problem `more correctly` ??

I am based in the U.K. - London - England - BUT these `unusual problems` can arise anywhere that there is Drainage.

As a `Postscript` - there could have been a `Problem` with the incorrect/ lack of VENTING to the Drain Run which did not cause any problems [noticeable] - UNTIL `combined` with a `partial blockage`- for example an `undersized` vent - which allowed `Air behind Water` - UNTIL the `Pressures`- Negative and Positive were `created`- which `overcame` the inadequate Venting - and THEN the W.C.`s [Toilets] and the Bath Trap [and others?] were affected - `Gurgling` Toilets and `Siphoned` Bath Trap.
An example of `Inadequate Venting` would be where a `Soil Stack`[U.K.] - the Main 4" Down Pipe
for `Toilets`[ W.C`s] - which had 2 Toilet pans discharging into it - had a 2" Vent Pipe - COMPLETELY INCORRECT/INADEQUATE - when the Toilets were `flushed` the volume of water [etc] filling the Stack - flowing vertically - would Siphon water out of the `traps` on the Toilet Pans - because the 2" [inadequate] Vent would NOT allow enough AIR into the Stack to prevent the water being Siphoned out of the Toilet Pans, this would also be incorrect for a `Stack` with One Toilet Pan discharging into it !

If the `Venting` is inadequate - when `Positive`or `Negative` Pressures build - up / occur - they cannot be `relieved` / `negated` by the Vent - as the Pipe Diameter/ Volume cannot either allow enough AIR out of / into the Drainage/ Above ground Pipework.
This results in the type of problem that you are experiencing.

Your Drainage `Venting` might have been `Accidentally Adequate` - BUT `TOTALLY INCORRECT` - for the `Normal` discharging of Water and `Toilets` - so no problems were noticed - UNTIL combined with the `Partial Blockage` - WHEN the problem then `came to light` ??

I hope that I have not `worried` you too much - THIS is a good example of a `Problem` that needs the investigative knowledge of a `Professional Plumber` - who would investigate the `Venting Issue` and check the Drainage System for any obstruction / `partial blockage`.

I really do hope that you find a `Simple Fix` for this - BUT above is `MY Theory` - of a `situation` which CAN HAPPEN - I would be `VERY INTERESTED` in the Solution - after YOU or a `Professional Plumber` / `Drainage Expert`- have solved the problem - will you please `Post` the outcome here.
"Good Luck" CHRISM.
 
Last edited:
Thanks for the reply. When this happened, the water level in both toilet bowls was very, very low afterward. So I guess that would indicate the siphoning you mentioned.

I suppose I'll need to call a plumber.
 
Thanks for the reply. When this happened, the water level in both toilet bowls was very, very low afterward. So I guess that would indicate the siphoning you mentioned.

I suppose I'll need to call a plumber.

IF you are confident in checking the Drainage for a `Partial Blockage` -you might be able to then unblock it ?
Although that would `aleviate` the present problem - you would still probably be left with a `Venting` problem.

I would NEVER discourage anyone from engaging a `Professional Plumber` or `Drainage Engineer` - but if you did a bit of `Investigation` - which can be `Time Consuming` - the information that you could supply to a `Professional` - even `Simple Stuff` - that they do not have to spend time checking - you might be able to save some money on what could be an `Expensive` problem to COMPLETELY rectify.

When I said to run a tap in the Bath - after emptying to re-establish the water which `seals` the Trap from the Drainage `Smells` and `Germs` - now that you have replied about the W.C. Pans losing some of their water - You MUST ensure that you `Flush` them after this happening - to reinstate the water `Seal` in those Toilets - OR you will have a LARGE pipe emitting `Foul Air` and `Germs` into your home.

IF the `Problem` causes the Flushing of the `Toilets` to siphon water from the W.C. Pans - as a temporary measure - you should `top up` the water level in the Toilets with a Bowl / Bucket - Don`t leave the water level down - as I explained about the loss of the `Seal` from the Drainage.

As before - "Good Luck" in getting this `solved` CHRISM.
 
Last edited:
Check the vent pipe that exits through the roof first. Make sure it is safe to climb up on the roof first. Look down the vent pipe with a flashlight and see if any blockage is obvious. You can flush the vent pipe with a garden hose.
 
Check the vent pipe that exits through the roof first. Make sure it is safe to climb up on the roof first. Look down the vent pipe with a flashlight and see if any blockage is obvious. You can flush the vent pipe with a garden hose.

TO GATORFREAK:


This is definitely worth looking at - but as I stated in my `lengthy` post - as the `Toilets` that are affected are at different ends of the property - it is `Unlikely` that ONE VENT PIPE is the cause of what was described [?]

If one vent pipe was blocked and this had caused a `Toilet` to be siphoned at the other end of the property - it would mean that this `Toilet` had either NO VENT or a Serious Problem with the `VENTING` on that side of the property.

While it is definitely good advice to `check out` the simple things - what you described sounds more complicated than a `blocked vent pipe`.

I have a `feeling` that my VERY long post will be viewed as `over complicating` the matter - hence the advice to check the vent pipe ?

I hope that you do have success with that - BUT - I assure you that when I included the fact that you must have `VENTING PROBLEMS` - if I thought that your description of `problems` at Toilets at opposite ends of your property was caused by ONE BLOCKED VENT PIPE - I would have advised you to check that it is `CLEAR`- before writing a very long `Post` on the matter.

I have experienced similar problems to yours which were caused by factors that I detailed in my `Main Post` about this.

For the `benefit` of other `Professionals` - I do not write my often very long posts just to `Complicate` matters - I feel that I should give as much detail as possible - so that the `Questioner` can see the `Problem` from various aspects.

We [Professionals] KNOW that there can be MANY different things that can cause `Problems` in Plumbing and Drainage Systems - quite often it is NOT the `simple / obvious` that is the cause.

If finding a blockage in ONE vent pipe and getting it cleared solves your problem - which I hope it does - please be `aware` that within my original `Advice` are `Clues` that the Other side of the property has `Venting Problems`.
Obviously it will be up to you whether to `Investigate` that further .

I would be grateful if you would let ME know - via a `Post` - WHAT happened to `resolve` your problem ?? - IF you do use a `Professional` can you ask them to explain to you what they found / rectified ??

As this may become a `Debate` between the supposedly `Complicated` and the blatantly `Obvious` - YOU could supply the `Answer` - with information on what resolved your `Problems`.

"Regards" CHRISM.
 
Last edited:

Latest posts

Back
Top