Causes of a Toilet Overflow: Cleaning Up an Overflowing Toilet and How to Prevent Future Toilet Problems

A toilet overflow usually occurs when a blockage prevents water and waste from flushing smoothly down the toilet drain. This backup prevents water and waste from flowing down the drain and results in your toilet overflowing. As your toilet backs up, clean water and waste will overflow the toilet bowl. If not cleaned up quickly, it may cause extensive water damage to your bathroom floor or even leak through the ceiling below. Other common causes of overflowing toilets are sewage backups, septic tank issues, low flow toilets, and malfunctioning plumbing.

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Common Causes of an Overflowing Toilet

There are a number of common causes that result in toilets overflowing. While most toilet overflows are caused by some type of clog, plumbing malfunctions, sewer line issues, and problems with septic systems may also cause issues.

Clogged Toilet Bowl

A clog in the toilet bowl causes most toilet backups. Clogs are usually caused by flushing the wrong things down the toilet. While your toilet is designed to flush toilet paper and waste, other items are likely to clog the drain.

Avoid flushing diapers, sanitary products, paper towels, or any solid items. Additionally, while so-call flushable wipes imply they are safe to flush down the toilet, they are actually one of the biggest causes of clogs.

Clogged Toilet Trap

Most toilets have an s-shaped trap that prevents sewer gases from backing up into your bathroom, causing terrible smells. Due to the bends in the trap, it is susceptible to becoming clogged for the same reasons as your toilet bowl.

Clogged Drain Pipes

Once the water leaves your toilet, it flows through drain pipes in your home towards the sewers. These drain pipes often have at least one, if not multiple bends. As a result, waste and other items can build up at the bends. Over time this will cause your toilet to flush slowly and can eventually lead to a back.

Clogged Lateral Sanitary Sewer Line

The next place water goes is to your lateral sanitary sewer line, which is the main sewer line that connects your house to the municipal sewer system. May non-flushable items, like sanitary products and so-called flushable wipes, often build up in the lateral line and cause a backup or toilet overflow over time. If this is the issue, you will typically have other drainage issues, such as a gurgling drain or backed up sink.

Improperly Working Septic System

If you have a septic system, an overflowing toilet may be a sign of a full tank or another issue. Have your septic system inspected by a professional to ensure it is in proper working order.

Low Flow Toilets

Many newer homes have low flow toilets designed to conserve water. While they do save on water usage, some low flow toilets are unable to effectively flush everything down the drain. Low flow toilet models produced before 1997 are especially prone to flushing issues.

Broken or Malfunctioning Plumbing

A malfunctioning tank float mechanism or a stuck handle may also cause your toilet to overflow. If the overflowing water is primarily clean water, inspect the inner workings of your toilet and replace broken parts as necessary. Contact a professional plumber if you are unsure what needs to be fixed.

Is a Toilet Backup Contaminated?

The water involved in a plumbing failure or toilet overflow is measured by the likelihood that it contains microbial or bacterial contaminants that can make you sick. Unless the toilet is completely empty when it overflows, it’s safe to assume that any toilet backup or overflow is contaminated.

Category 1 is clean water, which comes from a supply line and contains no contaminants. Category 2 is grey water, which comes from a source that may include some contaminants. Category 3 is black water, which contains significant levels of contaminants.

If the overflowing toilet only contains urine, the water is classified as category 2. If a toilet overflow contains solid waste, it is classified as category 3. Additionally, if overflowing water is not cleaned up, it will become contaminated over time with category 1 becoming category 2 and so on.

In the event that your toilet backup without flushing or in conjunction with a sewage backup, the water is definitely contaminated. Since a sewage backup is category 3 black water, you should assume that it contains significant health risks and take safety precautions when cleaning up.

How to Clean Up an Overflowing Toilet

When it comes to cleaning, you want to stop the flow of water first. Then work on removing standing water and cleaning up waste. You should also avoid using all plumbing until you identify the cause of the backed up toilet. This includes all toilets, sinks, bathtubs, shower, and laundry machines.

If you did not witness the toilet overflow, it’s possible that wastewater has soaked into flooring, baseboards, walls, or your vanity. In this case, you should call a professional sewage cleanup and water damage restoration company. They will inspect the area for lasting damage and restore your bathroom to its original condition.

1. Turn Off The Water

The first thing to do is stop the flow of water, even if the cause of the toilet overflow isn’t related to the water supply line. Most toilet supply lines have a shut-off valve on them, typically below the toilet tank near the floor.

If there isn’t a shut-off valve on the supply line, remove the toilet tank lid and pull the float up to stop the flow of water. Assuming this stops the overflowing, allow the toilet bowl to drain completely before releasing the float.

If the water begins to run once you release the float, you will need to turn off the main water supply line. If your toilet continues to overflow even with the water off, the problem is likely a backup from either a drain pipe or the main sewer line.

2. Use the Plunger on Your Toilet

Most toilet clogs occur in the toilet bowl or trap. Plungers are one of the most effective tools for resolving clogs. The up and down motion of a plunger creates pressure that forces the clog out of the blow, through the trap, and into your drain pipes.

Avoid using a basic plunger, as it won’t form an adequate seal to create the pressure you need. Instead, use a bell plunger that forms a better seal with your toilet drain. Apply a layer of petroleum jelly to the plunger for an even better seal.

The best time to use your plunger is before a toilet overflow occurs. Wait until the toilet overflow stops to try plunging. If it continues to overflow, a plunger will likely only make a bigger mess. While a plunger may clear a clogged toilet bowl or drain pipe, it cannot fix other causes of an overflowing toilet.

If there is a significant amount of water on the floor, temporarily skip ahead to step 4 and return once the damage is under control.

3. Use a Toilet Auger or Drain Snake

If you cannot unclog your toilet with a plunger, try using a toilet auger. Toilet augers and drain snakes work very similarly. However, toilet augers are specifically designed to work with the shape of a toilet and the s-shaped trap.

A toilet auger is designed to crawl through your drain pipes and snag the clog, allowing you to pull it back out of the toilet. In some cases, the auger will break up the clog enough that it will flow away from the toilet towards the sewers.

Again, skip ahead to step 4 if there is significant water or damage from the toilet overflow, then return to this step afterward.

4. Extract Standing Water and Waste

The longer water and waste sit on your bathroom floor, the greater the potential for damage. Water will absorb into walls and cabinets quickly and waste will allow bacteria to grow.

Use a wet-dry shop-style vacuum to suck up as much standing water and waste as possible. If you don’t have a shop vac, you can rent one from most equipment rental companies. Alternatively, you can use towels or blankets to absorb the water. Just make sure you get them into the washing machine after the issue is resolved.

5. Dry Out Damaged Walls and Cabinets

Once you’ve removed the bulk of the water, use high powered air movers or fans to dry out the damaged materials quickly. Air movers are available from your local equipment rental company. While you can use regular fans, they work more slowly and there is a greater chance of mold and bacteria.

6. Clean and Sanitize Your Bathroom

Begin by cleaning your bathroom with a multipurpose cleaning agent. Wipe down every surface, even those that did not come in contact with water from the overflowing toilet. Then use a hospital-grade sanitizer to decontaminate your bathroom and prevent mold and bacterial growth in the future.

You should clean and sanitize every surface in your bathroom, even those not affected by the overflowing toilet. Additionally, avoid using bleach, as it isn’t effective at killing mold. Most hardware stores carry the type of sanitizing agents you need.

If the Overflowing Toilet is Upstairs

Cleanup for an overflowing toilet in a second or third story bathroom is more complicated. Remember that the floor of the affected bathroom is also the ceiling for another part of your home. If sewage and water have permeated the floor, it may also cause ceiling damage below.

Even if you don’t see visible signs of water penetrating the flooring, it’s still safest to assume that it did. Depending on the volume of wastewater overflowing from your toilet, it may take time for signs of damage to appear on your ceiling.

If wastewater is dripping through your ceiling, you may need to replace that section of the ceiling as well as the bathroom flooring. While you can try to clean up this damage on your own, it’s best to contact a professional restoration company.

If the affected area contains a ceiling fan or a light fixture, do not turn it on. Turn off the electricity to your bathroom and the room below it in order to prevent the risk of electrical shock. If you smell smoke or see sparks, leave your house until a professional has addressed the problem and declared it safe to enter.

If the Toilet Backup Contains Sewage

In the event that the toilet backs up when not in use, the resulting toilet overflow will definitely contain sewage. This typically happens due to a clog in the lateral sewer line or due to the municipal sewer lines becoming overwhelmed during severe rainstorms.

If a sewer backup resulted in your toilet overflowing, it will contain not only waste but bacteria and other pathogens that pose a health risk. You should wear long rubber gloves, tall rubber boots, long pants and sleeves, and a ventilator when cleaning up sewage. It’s also recommended you wear a face shield to prevent getting splashed in the mouth, nose, or eye.

Preventing Future Toilet Overflows

The best way to prevent a toilet overflow is to only use it as intended. Only flush toilet paper and human waste down the drain. Keep a trash can in the bathroom for all other items, including baby wipes, diapers, soap, facial tissue, paper, fabric, and sanitary products.

Also, avoid using so-called flushable wipes. Although they do dissolve like toilet paper, they take much longer to break down and can easily cause clogs. Never flush fatty or oily fluids such as lotion or shaving cream down the toilet. Fats and oils will build up in drain pipes or clump together with other solids to form blockages.

How to Unclog a Toilet

If you need to unclog a toilet that has not overflowed, the most effective tool is a plunger. If the toilet is close to overflowing, use a bucket to bail out some of the water and waste. Then use the plunger to clear the clog. When unclogging a toilet with a plunger, use slow steady pumps to push the clog down the drain. If you have a hard time getting a seal, apply a layer of petroleum jelly to the lip of the plunger. If a plunger doesn’t unclog the toilet, use a toilet auger to snake the drain. Toilet augers are designed to get into the toilet drain and break up or pull out clogs.

Need Help With an Overflowing Toilet? We’re Here To Help

Restoration Local is a network of water damage contractors qualified to clean up after an overflowing toilet. You can choose your own water damage contractor from our list of major franchises like BELFOR Restoration, DKI Restoration, and Steamatic as well as independent restoration companies. For emergency services, call 1-888-443-3110 to speak with our on-call contractor now. All of our on-call contractors offer 24-hour emergency services, 30-minute response time, and a free estimate.

Photo by Chris Lattuada / Flickr

Author: Jeff Rooks

Jeff Rooks writes restoration content that helps homeowners restore their lives after a disaster or accident. Most days, you can find him cycling through Tampa. He also enjoys exploring new and delicious food and beverages around the world.

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