When your Cup Runneth Over: Part 1


Table of Contents

Read When your Cup Runneth Over: Part 2. As complicated as a toilet might look when you lift the tank’s lid, at the end of the day they are pretty simple devices. But making sure they are working properly is serious business. The first part of this blog post describes how a toilet works, and how to deal with a leaking toilet.

Toilet Troubleshooting: How not to Call the Plumber … and when you should

Understanding How the Basic Toilet Works

Toilets have a variety of designs, but for the most part, their operation is quite similar from one type to another. There is a bowl, that empties using suction action, and a tank, that refills the bowl and itself.

The process starts with pressing the handle, which raises the trip lever. This level in turn pulls upward on the lift rod (sometimes a chain), lifting the tank ball (sometimes a rubber flapper) and letting the water in the tank drop down through the flush valve into the bowl using the force of gravity. The water enters the bowl through both a series of small holes out of sight around the bottom of the rim of the bowl, and through a larger hole (the “siphon jet” at the bottom of the bowl.

1 - tank parts

The water flowing rapidly into the bowl from the tank raises the level of water in the bowl to fill the siphon pipe, and siphonic action then sucks the water from the bowl. Emptied of its original contents, and with the siphon now broken, further water flowing from the tank replenishes the bowl. As the water level rises slowly, the bowl will fill to the point where the bowl’s water level is at the point of the siphon again.

Meanwhile, the tank up above has largely emptied. Its low water level causes the tank ball to close the flush valve, and at the same time the float ball, now sitting low in the tank, allows the ball cock to open. Once open, the ball cock starts two flows of water: one flow through the tank refill tube fill the tank, and the other through the bowl refill tube to continue refilling the bowl. As the tank refills, the float ball rises, and the float arm eventually closes the ball cock.

2 - bowl parts

The tank also has an overflow tube, which serves a couple of functions. It allows the supply of water coming through the bowl refill tube to refill the bowl after the tank valve has closed, and it also provides a means for water to escape into the bowl if the water level in the tank rises too high. Otherwise, it could happen that the water in the tank would continue to rise and eventually overflow the tank, leading to a flood.

Finding the problem: When the toilet is running constantly

When the toilet is running constantly, one of three general problems exists (hopefully not more than one at a time): 1) the toilet has a leak so that water escapes to the outside of the toilet; 2) the ball cock is not closing properly; or 3) the trap valve is not closing properly.

Dealing with leaks running outside the toilet

3 - tank leaks

When water is leaving the system of the toilet altogether, it is often detectable by water on the floor in the area of the toilet. If the toilet has a cracked tank or bowl, or loose or rotted gaskets between the tank and the bowl, leakage is possible. In the case of a cracked tank or bowl, replacement is the only reliable solution. If however the gaskets sealing the bolts that connect the tank to the bowl are at fault, they can be replaced. Similarly, the seal between the flush valve and the bowl might be at fault and can be replaced. Some toilets have their tank and bowl as one piece of porcelain; for those, these gaskets are not an issue. Finally, leakage can occur through the entry point of the filler tube.

4 - bowl leaks

Another potential source of leakage is where the toilet connects to the floor. The bottom flange of the bowl joins to the drainpipe with a wax ring serving as a seal. This ring will prevent leaking water from leaving the toilet, and will also prevent unpleasant smells rising from the drain and reaching the bathroom. The wax ring can become ineffective through time or if the toilet is not securely fastened to the floor with mounting bolts. If so, it must be replaced. This type of leaking is particularly insidious as it might not lead to water on the bathroom floor, but water will instead enter inside the floor, possibly damaging the floor, its joists, and the ceiling of the floor below the toilet.

Finally, if you are interested in a history of toilets, and how they are made, this is a good three-part video series:

The Toilet

Part 1

Part 2

Part 3

When your Cup Runneth Over: Part 2

Most toilet problems are fixable with relatively little expense, skill, or tools if you are willing to roll up your sleeves. For those wanting to bring in a professional, contact Master Drain today for a quick solution.

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