Toilet flushing slow

If you have a slow flushing toilet in your bathroom, then you’re probably wondering what’s going on. You’re not alone! In fact, this is one of those problems that could perplex even the most seasoned DIY household plumber. If your slow toilet is old, then you might resort to the fact that it’s just tired. If only it were that simple…of course, that’s not even simple!

The first real guess is usually that there’s a blockage going on somewhere in the drain pipes. While this seems logical enough to cause a slow flushing toilet, in reality, it’s unlikely that it’s the culprit. Although there’s a chance, there is probably something else to blame. Now, you’ve probably figured that out if you’ve tried to snake or plunge your toilet with the slow flush and it hasn’t improved. Let’s take a look at some of the more probable causes…you might just be enlightened!

Causes for your toilet’s slow flush
As usual with this kind of plumbing, understanding how things are supposed to work will help you diagnose and fix issues. For a toilet to work properly, it needs an adequate amount of siphoning pressure. This is created by a volume of water flooding the bowl, which causes it to overflow over a trap in the back-bottom of the toilet. Think of the trap like a damn. And as if by magic, once the damn allows a gush of water to spill over, everything behind it follows until there is no more. And by everything, we know what that is…it’s the waste water and debris, if you will, contained within.

When the bowl empties, that means the water has all siphoned out after the initial gush, which is provided by the flood from the tank after you lower the lever. If your toilet is flushing slow, then you may have a problem with the flood waters. Something may be causing the water needed to flood the bowl properly to not do so adequately or in a timely manner. Read the next section to investigate.

How to fix a slow toilet
Now that you know what to look for, it’s time to take note on what you see going on in your slow toilet. These fixes can also apply to a toilet not flushing completely. Ok, here are the two most common reasons:

  1. Hard water is to blame! Yes it’s true, if you have hard water, a toilet is not immune to it’s trouble-making. As mentioned above. water may be slow to get to your bowl because its pathway(s) are partially blocked. Little holes that ring around the underside of your toilet’s rim may have calcium deposits caked in there. The easiest way to knock it out is with the end of a coat hanger you don’t mind parting with. Carefully ream out the siphon and rinse holes. It’s a little dirty, but lower your head in until you can see them. As an added measure, to speed up your toilet flush, drain your tank (turn off supply and flush), then block the holes just described. Use wet paper towels and plumber’s putty to do this. Then, pour CLR (mineral removing agent/cleaner) down the overflow stack in your tank. Let that sit over night, or longer if you can. It will help eat away any remaining mineral buildup. You can also use hydrogen peroxide, which is a lot cheaper.
  2. Check the water level in the tank. It should be around 1/2″ from the top of the overflow tube. If it’s too low, the tank may not be filling enough and thus, providing too little water for the flush. This can certainly make your toilet flush slowly. You can also try just raising the float arm by bending it up. You may need a new one, but make sure it is high enough to get the water level higher. Remember, if it’s set too low, the water will stop filling.
  3. If neither of the above approaches seems to work, you may indeed have a bigger issue causing your slow flushing toilet. There may be a partial obstruction in the waste line, inefficient venting (which helps to equalize pressure in your plumbing) or you may have a low-flush model that needs a little more water pressure to work correctly. In these cases it’s best to higher a plumber. At least you can tell them what you’ve tried, and what you might expect be behind your toilet flushing so slowly.
