Pencil Test
Take your pencil and draw a line on the back wall of the tank, and on the waterline on the interior of the tank. Shut off the water supply and wait for 30 minutes. The leak is taking place at the refill valve (located on the left side of the tank) if the water is still at the pencil mark.
Although water may not be seen or heard running, your toilet may have a silent leak. Here is a simple Toilet Dye Test you can complete to see if your toilet is leaking. Drip 10 to 15 drops of food coloring into the toilet tank.
The three most common types of toilet leaks are in the flapper, the water supply line, and the wax ring under the toilet. For each type of leak, the first way to try to identify where the leak is coming from is to do a visual inspection. Often, you'll see evidence of water leaks.
A toilet that cuts on and off by itself, or runs intermittently, has a problem that plumbers call a "phantom flush." The cause is a very slow leak from the tank into the bowl. This problem is almost certainly caused by a bad flapper or flapper seat.
The most likely cause is capillary action. This happens when a piece of debris, wicks the water out of the bowl and down the drain. It could be something as small as a string. Another possibility is the drain venting in the home is not sized properly, or a clogged vent.
The most common toilet leak is caused by a deteriorated flush valve (flapper) at the bottom of the toilet tank. If the flapper does not seat properly, water will leak into the toilet bowl. Often this leak will occur without being heard.
Splash leaks are simply water escaping past a shower curtain or a shower door. Plumbers tell us it's the most common type of bathroom leak. Although it may sound minor, this leak causes major damage when water seeps into the subfloor where flooring meets the tub or shower.
The base of your toilet is held to the ground with two bolts called tee bolts. If these bolts loosen, the toilet will likely rock, causing the seal formed by the wax ring to break. Drain water may seep out of the base each time you flush the toilet if your tee bolts are very loose.
A flapper that doesn't seat properly can also encourage water to drip constantly. Plumbers diagnose the exact cause of this problem by removing the toilet tank lid, flushing the toilet. they can spot signs of tube leakage, flapper malfunctions, and problems that prevent the ball float from rising to the fill line.
Water leaks can occur behind walls, but they can also occur in the following areas of a home: toilets, under bathroom and kitchen sinks, in the bathtub, in the shower, the icemaker water supply line, and in washing machine hoses.
A leaking toilet can be annoying and wasteful. To check if your toilet has a leak, place a few drops of food coloring in the tank. If coloring is seen in the bowl without flushing, you have a leak.
The only-when-flushed toilet leak could be caused by loose mounting bolts or a worn-out wax gasket while the all-the-time leak could be caused by a loose water supply line connection, a problematic water shutoff valve, or a faulty seal between the toilet tank and its base.
The most common place for a toilet to leak is at the wax seal. Replacing a wax seal may be as cheap as $50. Other common leak points are the tank and bowl which may cost $300 or more to repair. You should take care of leaks as soon as possible so you don't add water damage to the list of necessary repairs.
Your water and sewer bill could double or even triple in a quar- terly billing cycle. About 20 percent of all toilets leak. Most toilet leaks occur from the tank on the back of the toilet into the bowl, and then into the sewer. They might not make much, if any, noise.
What's the price range for a typical toilet leak? Expect to pay $150-$500 USD—but likely closer to $150-$175. In the U.S., the average plumbing repair costs a bit over $300 USD, but that includes repairs that are more complex than most toilet leaks.
While toilets are meant to last several decades, they do have a limit. If you know your toilet has been around longer than you've been alive, then there's a chance that it's likely on its last leg already. A general rule of thumb is to replace a toilet around every 25 years, though your mileage may vary.
Since the water flows down the sewer, leaking toilets don't necessarily leave any signs of a leak, until you get the bill. The average leaky toilet can waste about 200 gallons of water per day. That's over 6,000 gallons a month ($70.06*) for just one leaking toilet!
Loose or worn out tank-to-bowl connections.
The tank and bowl in two-piece toilets are bound together by a collection of gaskets, nuts and bolts. If any of these parts come loose, a leak can develop at that area in the toilet.
Again, leaky water is a telltale and common sign of a bad wax ring. If you do not regularly see moisture or puddling water under your toilet, you may be fine. Leaks can, however, happen where you do not see them, under the finished floor and into the subfloor.
A toilet making an air noise or a whistling or hissing sound is a sign that the fill valve is not closing and sealing properly, and air or water is leaking from the fill valve. If the fill valve isn't closing properly, begin by replacing it. If this doesn't solve your problem, call a plumbing professional.
In cases where the dripping sound is coming from the toilet tank itself, tightening the overflow or replacing the flange, ensuring the flapper fits properly over the drain, and adjusting the float valve so the tank fills to the line and not over it can all help remedy the issue.