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

So you don’t exactly know what to do when your toilet overflows, but you do know that the problem is positively maddening. Wait—now it’s draining toward empty? What gives? Fear not! The solution to an overflowing (and slow-draining) toilet may be simpler than you think. Let's dive into why this occurs and what steps you can take to deal with it.

Pro Tip

A few warning signs that something is wrong with your system include a constant gurgling, slow-flushing toilets, bad odors, flooding in the yard, and a washing machine that's not draining properly (your clothes are still soaking wet after the spin cycle). Reach out to a pro if you think something may be wrong.

Melissa Erickson

Vice President, AAA Dependable Cesspool, Sewer & Drain

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

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

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 simple and 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 due to an accumulation of, um, debris of any kind. 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 dislodge or remove the blockages manually.  

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, then 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. In some cases, it's a one-off problem that will be resolved when you do this. 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 still isn't fixed, it's best to call a local plumber 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

To fix this problem, all you need to do is clear any debris away from the vent. But if you're not comfortable getting on the roof, hire a pro to help. You can also install a vent cover that will help prevent future blockages. 

One More Step: Testing the Toilet

Photo: petzshadow / Adobe Stock

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

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.

D.P. Taylor contributed to this piece.