Why Your Toilet Fills Up With Water Then Slowly Drains (and Potential Fixes)

You may not know what to do when your toilet overflows, but you know that the problem is positively maddening. It’s even more confusing when it starts to drain toward empty. Luckily, the solution could be a simple fix. Let’s explore why a toilet fills up with water and then slowly drains and the steps you can follow to get it working again.

5 Causes of Toilet Water Rising Then Slowly Draining and Solutions for Each One

Plumbing maintenance ensures your toilet works effectively and at maximum capacity. If the water in your toilet keeps rising and then slowly draining, keep reading to find common problems and solutions to fix the issue.

1. Sediment Buildup in Rim Jets

A toilet that overflows and then drains completely is a telltale sign that it's not the big hole on the bottom of your toilet that's the problem, but the little holes around the rim of the toilet you don't see. These little holes are known as rim jets, and their purpose is to create a swirling motion when you flush the toilet, which helps force the contents of the toilet down the drain.

After a while, sediment can collect along these holes, which often goes unnoticed because you don't see them. When this happens, the water pressure drops, and you don't get proper water flow or a full flush when you hit the handle. Instead, the water rushes in, fills up the bowl more than it should, and then slowly drains.

Solution

The fix for this problem is fairly straightforward. Start by identifying the mineral deposits using a small mirror to help. They'll appear as a light, even color across the holes. Darker colors suggest it's bacteria rather than mineral deposits. 

Once you identify the deposit, directly apply a mineral remover and wait for a few minutes to let the remover dissolve the materials. Finally, grab a screwdriver or some strong wire to chip away at the deposits. Feel free to do this with a heavy touch. They often require some elbow grease to remove, even when using mineral deposit remover. 

After chipping away the main deposits, grab a toilet brush and give it a once-over to remove any remaining residue.

2. Drain Blockage

In some cases, a blockage might be the cause of a slow-draining toilet. These blockages can happen when inappropriate items are flushed down the toilet or when debris accumulates. Malfunctioning plumbing, like a broken valve, can also create blockages in the toilet. 

Solution

First, try using a plunger to loosen the block. Place it over the drain to form a seal and pump it up and down a few times. In many cases, this is enough to clear the block. But if that doesn't work, insert a plumbing snake into the drain and attempt to manually dislodge or remove the blockages. 

3. Water Level in Tank

Low water levels in the tank are a common cause of a slow-draining toilet. This can happen due to leaks, evaporation, overuse, or a broken flush tube. If you recently had guests over and your toilet saw a lot of action, you might only have to wait until the guests leave for the problem to resolve. However, if that's not the case, there are a few potential solutions.

Solution

You can manually refill the tank with water to help the toilet flush. Sometimes, this is enough to resolve the problem. If not, check the flush tube to ensure it has no bends, leaks, or cracks. If it appears damaged, buy and install a new one to fix the problem. If the problem persists, it's best to call a local toilet repair pro to help. 

4. Faulty Flush Flapper, Chain, or Handle

Toilets have a flush flapper attached to a chain, which is attached to the toilet's flush handle. If the flapper, chain, or handle is broken, it can lead to backups and slow-draining problems. 

Solution

Lift the tank lid and examine the flapper and its connected components, then give your toilet a flush, looking for any issues. In some instances, the chain might be too loose, so it's not pulling the flapper up high enough for an adequate flush, in which case you can tighten it or replace it with a new one. If the whole system isn't working, replacing the flapper and its components with a new one is a relatively easy installation for most homeowners. 

5. Lack of Proper Ventilation

If you notice a foul odor in your home, you might have a venting problem on your hands. Many roofs feature a sewage vent stack that promotes airflow through your plumbing and allows water to flow freely. If the vent is blocked by leaves, debris, or even small animals, it can affect how well your toilet flushes.

Solution

Climbing up on the roof is a risky endeavor that can result in injury, so it’s best to call a pro to handle this one. They’ll clear debris away from the vent and install a vent cover to help prevent future blockages.

One More Step: Testing the Toilet

Once you're satisfied with your cleaning job, flush the toilet to see how it performs. If the toilet still overflows and drains completely, but you've noticed some improvement, then you’re on the right track and need to keep chipping away at the buildup.

Tips to Avoid a Slow Draining Toilet 

Cleaning and prevention go a long way toward preventing a toilet that drains slowly. Practice these tips to keep your toilet working correctly and avoid debris buildup before it happens. 

• Stay on top of regular maintenance like cleaning your toilet and checking for malfunctioning parts. Check for leaks at the base, water supply line, and tank-to-bowl connection. Also take a look at the water level in the tank and the flapper seal. 

• Clean your toilet tank to prevent mineral deposits from forming and creating issues for the interal components. Keep the jet holes and toilet bowl clean as well. 

• You may be tempted but we recommend keeping drop-in toilet cleaners out of your system. Tablets containing bleach and chlorine can wear down toilet components, like gaskets, washers, and flappers, leading to a leaking toilet. 

• Use your plunger to clear clogs so they don’t interfere with how your toilet flushes and drains. 

When Should I Hire a Pro to Fix a Toilet That Overflows?

If the problem persists after multiple attempts, it may be time to throw in the DIY towel. Stubborn buildup could be a sign of hard water or a sign it’s time to replace your toilet.

Either way, contact a plumber near you to recommend a course of action rather than wasting hours trying to diagnose your issue. The average cost to repair a toilet is $240. When you've got a toilet issue, it's best to deal with it as soon as possible, so don't delay.