Gurgling toilets

[Bob Mulloy]

Message from client, any advice?

"All three toilets on first and second floor have gurgling noises when you flush, and I would guess that there is not a large enough air vent pipe supply. Any suggestions for what might be done to remedy that? They flush fine, but the air gurgling noises they make at the beginning of the flush sound like they may not flush.. but then they catch enough air and away they go... Not a big deal, just checking to see if you have any suggestions."

[fqp25]

Have a plumber check the vents from the roof, maybe stick a rod down them, to check for blockage. Or better yet, if possible a sewer camera.

[inspector57]

Check the vents. If typical roof vents, leaves and such can easily clog the vent.

From the description, I don't think that would be the issue, though. Now if the trap sucks partially dry or if water moves in one toilet when the other is flushed, I would suspect venting. Noise may just be the toilet design.

JMO

Jim

[John Dirks Jr]

I will add a question that might lead to another possible answer.

If there is a backflow preventer, could it be causing the delay? It waits for a slight bit more pressure to build then it opens and woosh....down it goes.

Are the occupants new to the home? PVC drains are typically make more noise then the various metal drains. Maybe their old house had metal and they just are not used to the extra noise.

[fqp25]

Originally posted by AHI

If there is a back flow preventer, could it be causing the delay? It waits for a slight bit more pressure to build then it opens and woosh....down it goes.

Do you mean a toilet with a backwater valve? (Like a Check Valve?) Do they make those?

Back flow prevention should be in the ballcock or fill valve.

[John Dirks Jr]

I mean backflow preventer in the main drain line.

[Scottpat]

It might be the type of toilets and and the type of vent. If they are discharging into a wet vent, the following could cause what you are describing.

With some of the better modern toilets (Toto) they discharge all of their water very quickly. This is what makes them flush so well with a small amount of water. All of the water is entering the vent stack quickly and with a large volume. This does not allow for the vent to vent properly as the entire pipe is full of water that is flowing down. This then forces an air bubble back through the traps on the other toilets.

This was not a problem with the older toilets as they released their water slower and it did not fill up the vent stack with a big blast of water. Same holds true for the newer cheap toilets that do not flush all that well.

The only solution I know of would be to increase the size of the vent pipe or put in a old or cheap toilet.