Toilet 101: Basics and Common Fixes


Everyone should know how to fix basic problems with their toilet. General toilet knowledge is a good life skill to have, it will save you money, and give you something to do when football isn’t on. I didn’t know much about toilets and decided to dive right in when I had a problem. Even though toilet issues can be simple, it took me 3x as long to solve my problem than it should have!

So, here is all the information I wish I had prior to pretending to be a handyman. I’m in no way good with a wrench, but being a Systems Administrator means I’m good at diagnosing and fixing things, so solving my toilet issues was just another troubleshooitng excercise.

Toilet Basics 101

First, lets begin with toilet anatomy. A lot of trouble can be avoided if you learn what you are dealing with before you attempt to fix it. A toilet is pretty simple, as the following will illustrate. Do note, that this is a slightly older technology, and various different types and designs of filler valve / float combinations exist, but this will serve as a good primer.

Toilet Anatomy


  • Water comes from the wall and through a hose into your toilet (not shown)
  • Follow the hose coming out of your toilet. The water can be shut off by twisting the knob at the end of this hose – clockwise to turn the water off, counter-clockwise to turn it on. Turning water off from here will prevent water from getting to your tank and bowl. You will often turn water off when you are working on your toilet.
  • The water goes through the hose and into the filler valve, which is the tube where water enters the toilet. The filler valve has various locations from which water will exit into the tank, not just the top of the tube.
  • While the tank is being filled, water also goes through a small hose attached to the filler tube and into the overflow tube. Water which enters the overflow tube bypasses the flapper (flush valve) and ends up in the bowl. Without this, your toilet bowl would be empty, as the flush valve/flapper stops water from entering the bowl.
  • As water fills the rear tank, it will eventually press upwards onto the filler float, and once the threshold is hit, the filler valve stops the flow of water into the tank and your toilet ends up with water in the tank, and water in the bowl.

Toilet Flushing Action

Now that you know the general anatomy and various parts to a toilet, you should also know what happens when you flush. As most of you will have reached this page because of a slow filling or slow flushing toilet, this should prove to be very informative. There is nothing fancy or techincally complicated about a toilet. A toilet is simply a fixture illustrating how physics works. A toilet flush, boiled down to its simplest form, is just using gravity to pull enough water from the tank into the bowl through the small fill holes underneath the lip of the rim, fast enough to push it down the bottom of the toilet and starting a siphon, which helps the water get into the pipes below the toilet and eventually out to the sewer or septic system.


>> CLICK IMAGE FOR FULL SIZE <<flush action final

Photo Courtesy of LazyPup, 3/20/2012


Diagnose The Problem

Diagnosing the issue with your toilet is the first step – you don’t want to jump right in replacing parts before you know whats going on. An accurate diagnosis will also prevent many headaches and save you money. The following sections I threw together about various toilet troubles I’ve had.

Slow Tank Refill

If it takes a long time for your tank to refill, you may have to turn the water off and check the line from the wall for debris. You may also need to replace your filler valve (~$15-30 at your local hardware supply store), which is responsible for filling the tank. A few parts within the fill valve itself are serviceable and/or repairable, but at a cost of about $5-10 each, you might be better served just replacing the filler valve all together.

A good test is to take the top of the tank off and set it aside, and flush the toilet. If water is entering the overflow tube at a slow rate, then you may need to replace your filler valve. Water should literally be shooting down the overflow tube very forcefully.

Toilet Doesn’t Flush Properly

You hit the handle and the toilet water just spins, or goes down very slowly, with a nice gurgle at the end. Naturally, the first thing you think is “clog”, so you run and get some Drain-O, but a whole bottle doesn’t seem to fix it.

The first thing you should do before grabbing Drain-O, is to fill a small vase/bucket full of water (at least 1gal), and dump it fast into the toilet without flushing. The sudden influx of water should cause physics to take over and your toilet to flush. If it does, then you know the toilet is not clogged, but you are not getting enough water fast enough from the tank into the bowl to start physics in motion.

You have a couple of options if that is the case: diagnose and fix the filler valve, or if your toilet is extremely dirty, simply using some CLR or other foaming-action cleaner and squirting it under the rim of the bowl to clean the filler holes. Some people report that after just a thorough cleaning of those holes, their toilets began to operate better. In my experience, although this helped, a new filler valve helped a lot more than just cleaning.

If dumping water into your toilet doesn’t cause a flush, then you probably have a clog somewhere in the s-shaped tube built into your toilet, or further down the pipe. Drain-O can help here, but some obstructions need to be pulled out with an auger (snake). If thats the case, you can always get an auger for about $10 at your local hardware store and attempt to fish out the obstruction by yourself before paying the plumber fees.

Noisy Refill

A noisy refill can be caused by a bad fill valve seal, which is a small gasket underneath the cap on top of the fill valve on such models as the Fluidmaster 400. This is an easily serviceable part, and at $5-10, is only slightly cheaper than replacing the whole fill valve itself.  If your only problem is a noisy refill, you may want to check this. But since multiple things can be wrong at once, you should just replace the filler valve if you can spare the extra $10.


I’d recommend starting with the simple fixes here. They cost roughly $20-30, and an hour or so of your time. If all else fails, call a plumber, but at least you will have attempted to save money, and will have learned something in the process.

I Hope this helps.


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