How to fix toilet dripping noise?

Dashi Powder

Every time some liquid goes into the toilet bowl even without flushing (I have tried as an experiment), a clear dripping sound starts. It sounds like water hitting a surface or dripping inside the wall. This noise lasts for about a minute or two every single time. It feels annoyingly loud at night especially when I just want to get back to sleep after using the en suite.

What I know:

•No visible damage: There are no water stains on the walls, no puddles on the floor, and no damp spots around the bottom of the toilets.

•No smells: There is no bad smell or sewer odour.

I have tried:

1. Get a plumber replaced the flush valves in both toilets. This did not fix the noise. He thought there might be a leak under the house. However, there is no access to get under the floor, so he couldn't check and left.
2. Get a second plumber to put a camera down the outside sewage pipe. He didn't see any leaks. He thinks that because the house is built on a slope, the pipes are possibly at an awkward angle. This might be causing water to drip slowly or echo inside the pipe after a flush. He suggested me to leave as is.

I am wondering if there's any way to find out what's causing this or any suggestion for a fix? Many thanks!

EricL

Hello @Dashi Powder

Welcome to the Bunnings Workshop community. It's sensational to have you join us, and thanks for sharing your question about your toilet leak.

Please note that plumbing work needs to be completed by a licensed professional for safety and compliance. 

I propose engaging the services of a leak detection specialist. Specifically, the one that offers both cable camera tracking and thermal scanning service. This will allow you to scan your drains and walls and get a full report. They will show you where the possible leak may be originating from, and the steps you'll need to make to address that leak.

However, I suggest doing a simple test and turning the cistern taps off on your toilets so that no water is flowing into the cisterns (it could be a very slow leak). If the dripping stops, then it's highly probable that there is a leak in your toilet that the plumber may have missed.

Let me call on our experienced members @Dave-1, @Noyade and @Nailbag for their recommendations.

If you need further assistance, please let us know.

Eric