Why is My Toilet Draining Slowly?

You’re used to your toilet giving off that definitive roar when you flush it, but you know that something’s wrong when there’s only the slightest whimper as the toilet water rises then slowly drains. A slow draining toilet is also an ineffective one, often requiring two, three or even more flushes to do the job that should be handled in one, which can rather unpleasant in addition to wasting water. In short, the toilet is failing at its primary task, which is to quickly whisk away waste out of your house and into the sewage system. Yep, you’ve got a problem, and you need to figure out why your toilet is draining slowly before it gets worse.

Understanding the Importance of a Quick Flush

To understand why you should care if your toilet flushes quickly, you have to understand how a toilet works. When you flush your toilet, the flushing action triggers an influx of water from the tank into the toilet bowl before traveling down the main waste line. The speed with which this water travels creates the suction required for the actual flush. The slower this water moves, the more ineffective the flush — and the larger your problem becomes.

How to Fix a Slow Draining Toilet

Fortunately, in many circumstances you may be able to fix a slow draining toilet on your own, without needing to shell out for pricey repairs. The exact remedy will vary depending on the reason that the toilet is not performing optimally:

• Obstruction in the pipes: When a toilet flushes slow but is not clogged, the first response can still be to reach for the plunger. In many cases, this is the right course of action. An obstruction in the pipes can still slow down the water without fully blocking or clogging the drain. A firm seal with the plunger can often dislodge this obstruction, or you can send a toilet auger or snake down the drain hole. If the problem persists after your efforts, it may be caused by something else.
• Low water levels in your tank: If your toilet tank doesn’t fill itself to the recommended level, you won’t get the speed and pressure that you need for an effective flush. Typically, water should rise until it is about an inch below the top of the overflow tube. You might be able to remedy this problem as easily as modifying the float level to allow for a higher fill.
• Mineral deposits in the toilet tank: Another reason the tank might not fill completely after each flush is because of mineral deposits that build up over time. If the buildup is severe enough, the float can close earlier than it should. If this appears to be the case, simply clean the area to remove the buildup. You may also have to replace a couple of parts. This may include the flapper, as mineral deposit accumulation can hamper the seal your flapper provides. Fortunately, replacing your flapper isn't too expensive.
• Clogged flush holes under the rim: When you flush, water from the toilet tank shoots into the bowl through small holes under the rim, which can become clogged over time and slow down the flow. A wire or other small, pointy object can clear out the obstruction and restore the flushing power of the toilet.
• Problems with the flushing mechanism: Open the bowl to check the flapper — the rubber piece located on the bottom of the tank. If the flapper is not sealing tightly, or if the chain connected to the flapper is broken, it will affect your flush. Adjust the flapper until it gives a tighter seal, or purchase a new one that will perform the job more effectively.
• Blockage in the roof vent: The drainpipe that the toilet empties down has a vent that runs up to your roof, which can cause problems in the flush if it gets clogged by debris. Gurgling sounds in your drains are one tell-tale sign of a vent obstruction. If you can access your roof, you can ensure that nothing is blocking the vent, and use an augur to remove debris from further down the pipe.

If your slow flush doesn’t appear to be based on any of these possibilities, it’s time to call an experienced plumber who can help troubleshoot your problem and get your toilet back to normal as quickly as possible.