Old or new, the sound of toilet should be consistent and uninterrupted all the way through the flush. Everyone notices a change in their toilet’s behaviors. Certain sounds can indicate problems that can be fixed with a few simple adjustments. Others, are indications that major plumbing problems are needing attention. 
The primary sound of a properly-working toilet is the “rush” of water. If sounds emanate from a commode while idle however, or long after use, there might be a need for a professional plumber. Here is a short list of common sounds that many people hear from toilets in need of attention.

The Post-Flush “Clunk-Clunk”

During a flush, the force of gravity washes several gallons of water from the toilet, into a piping system. Hard clunking is an indication that certain return valves have worn, and need replacement. Toilets work similarly to any other fixture in a house. They require an “in” line and an “out” line. With every flush, air pockets and materials are directed into larger pipes in a sewer system. If air and other materials are not properly regulated, back-flows can happen. This results in strong irregularities in the sewer line, and noticeable loud sounds that seem to come from the toilet. Only a qualified plumbing expert can pinpoint the exact location of a recovery valve that is not working properly.

The Mid-Flush “Whine”

As water is rushed into a sewer line, tremendous amounts of air will be sucked into the line if seals are not holding. Whines are the sound of air being pulled into the lines during flushing. A perfectly sound toilet will have tight seals around the floor mounts, the closet/bowl connection, and in the graduated piping which leads to the sewer lines. Seals that are failing will pull air from tiny failure spots in order to complete each flush in a vacuous atmosphere. The whine sound will eventually cease, but that means a major leak is imminent.

The Hard “Thump” When The Toilet Isn’t Being Used

This sound is common in multiple living unit buildings. Every time a toilet on a shared line flushes, there is a vacuum that must be distributed. Ideally, it is forced into a larger line. When pipe connection failures happen, these vacuums can back into other sewer lines. The “thump” is the sound of rushing materials and water trying to find its way to the sewer’s main line. Again, this is a major problem that needs to be fixed by an experienced professional plumbing service.

Any sound coming from the body of a toilet can be stopped with a little attention from the toilet’s owner. Scraping sounds usually happen because the flush handle is not sitting properly on the surface of the closet. Strained sounds can be fixed by cleaning the deposits clogging the outlets on the underside of the bowl. Metallic sounds can be silenced by adjusting the chain and lever of the flush handle to an appropriate length.

Persistent and extremely loud sounds that come from the toilet are always a sign that a major problem is affecting a toilet, or an entire sewer line. This is one of the most vital appliances in a home, so never let a mysterious toilet sound go unchecked.