Most plumbing problems are caused by repeated use and wear over time. A slow draining sink is one example of gunk buildup over the years that causes a plumbing problem. A leaky faucet handle is another plumbing issue you may have come across. It just has a worn-out part. Perhaps you’ve come across a water shutoff valve that doesn’t want to shut off. It’s stuck in place by mineral deposits.

Then, there’s the mystery of the running toilet. Why is it running? You jiggled and wiggled the toilet handle. You even took the toilet tank lid off and played with the flush lever, chain, and flapper. That bandaid sometimes works a little while. Finally, after a few days and nights of tolerating the running toilet refilling every 30 minutes, you get serious about finding a solution.

We don’t mean to make light of a running toilet. The fact is, a running toilet can waste about one gallon of fresh water per minute. That’s 1,440 gallons of wasted fresh water in a 24-hour period. Running toilets deserve immediate attention, and MN Roto-Rooter Plumbing and Water Cleanup is here to help.


The first step of solving the running toilet is to confirm you do have a water leak and the rate of water loss. If your toilet is frequently or constantly running, you obviously have a leak somewhere. However, most toilet leaks are silent. So, this guide is good preventive maintenance even if you think your toilet is fine. To check for a water leak, you have two easy options.

  • Leak Check #1: Turn off the water shutoff valve behind the toilet. Remove the lid to the toilet tank. Using a pencil or crayon, draw on the inside of the tank at the water line. Wait one or two hours. Check the pencil or crayon mark you made to see if the water level has gone down. If the water level has gone down, you have a toilet leak.
  • Leak Check #2: Remove the toilet tank lid. Squirt several drops of food coloring into the water in the tank. If you have a toilet leak, the colored water will leak into the toilet bowl in a short amount of time.


The fill valve is the tall plastic piece sticking up in the tank. The float arm and float are connected to the top part of the fill valve. When the toilet is running, lift gently on the float. If the running water stops, you simply need to adjust the float arm to lower the float in the water level. This will activate the fill valve and float’s automatic water shutoff mechanism. Some float arms may simply be bent. Others are adjustable by a screw.


Remove the lid from the toilet tank. Flush the toilet. The flapper is the rubber piece that flipped open when you flushed. It allows water to flow into the toilet bowl. After a few seconds, the flapper begins to slowly lower back onto the flush valve to stop the flow of water into the toilet bowl.

Over time, flappers can become stiff and brittle. At this point, the flapper won’t be able to keep a water-tight seal with the flush valve. Another common problem with the flapper and flush valve is mineral deposits. Minerals deposits are bound to happen on the flapper and flush valve at some point. Whether the flapper and flush valve have mineral deposits or the flapper has become brittle, your best option is to call your plumber to fix the problem.

If you want to try the DIY fix, purchase a new flush valve assembly, including all the hardware for the flush handle, chain, flush valve, fill tube, flapper, and bolts. These kits are reasonably priced. However, it does take some know-how to install a flush valve assembly kit and extreme caution. You do not want to crack your toilet tank or toilet bowl at the bolts or flush valve during the installation (it’s very easy to make this mistake). Follow the installation instructions included with the flush valve assembly.

MN Roto-Rooter Plumbing and Water Cleanup is dedicated to providing the very best plumbing and water cleanup services in Minnesota. We are available 24/7 for plumbing emergencies, and we never charge overtime! Call us at (320) 207-1079, or connect with us through our online form.