A floor drain that is discharging water out of the drain continuously is unsightly, unhygienic, and puts the health of people in the building premises at high risk.

A common conclusion that many people reach after noticing water back up is that the floor drain is faulty. It need not always be so. Water back up can indicate an issue in the plumbing system.

A floor drain back up needs immediate attention and rectification so that it does not cause more serious and expensive plumbing issues in the future.

Why is my floor drain backing up?

What is the Purpose of a Floor Drain?

A floor drain is part of a building’s plumbing system, installed to remove water in the area surrounding the fixture. The area around the drain is sloped to allow easy flow of water into the drain.

Floor drains are common in residential basements. They are usually positioned close to a water heater or dryer. In some residential settings, drains may be used in bathrooms and garage.

In commercial buildings, drains on the floor are commonly used in basements, kitchens, shower and laundry rooms, restrooms, refrigerator rooms and in locations close to swimming pools.

Floor drains come in rectangular, square and round shapes. Gratings – components that are used to the cove - are available in plastic and metal.

The grating is the most visible part of the drain. Other components of a drain system include a trap (also called a sediment bucket), a p-trap positioned under the drain, a drainpipe and a backwater valve.

The purpose of the sediment bucket in this system is to collect solid debris such as grit and sand. It also prevents sewer gases and offensive odors from entering living areas.

A strainer is also an important component of this system. A strainer prevents slip-and-fall accidents, and entry of foreign objects including small animals such as rodents.

In the absence of a drain, sewer water and surface water do not have an outlet to flow away from the building. Without a floor drain, building basements can get flooded with dirty water, leading to numerous health problems and structural issues in the building.

Stagnant water, for example, can seep into the building foundation and over time, compromise its structural integrity.

Reasons for Floor Drain Backing Up

If you notice water backing up from the drain in the basement, any of the following could be a possible reason for the backup:

Clog in the Drain or Sewer Line

Any clog in your building’s drain or sewer line can result in water back up from the drain.

A floor drain is an outlet positioned at the lowest point in your building. When wastewater finds no way to flow through its usual outlets - the clogged sewer line or the main drain line - the next best thing it can do is to flow into the floor drain.

When wastewater backs up from the main drain or sewer line, escaping water builds up in the floor drain, leading to water overflow and water back up from the floor drain.

One possible for a clog in the drain or sewer line can be damaged lines. Damages such as cracks create space for debris such as soil, dirt, grit or solid objects.

This results in a clog in the line, leading finally to water back up from the drain. Fixing such plumbing issues requires expertise and is best left to a professional plumber.

Damage in the Sewer Line

 Damages in the sewer line can be in the form of:

  • Cracks or holes in the line
  • A sagging or collapsing sewer line
  • Tree roots causing a serious clog or damage to the sewer line

Cracks or hole in the sewer line causes the soil in the surrounding area to enter into the system, which leads to heavy clogging over time in the sewer line.

Tree roots infiltrate the pipeline causing a clog; over time, they can lead to serious pipe damages. A sagging or collapsing sewer line becomes a clog by itself.

All the above factors cause wastewater to accumulate in the drain line and cause water back up over time.

Unlike a clog, a sewer line damage demands more work for correction. A video inspection of the sewer line is usually performed to identify the exact problem location.

Lack of Proper Maintenance

Good maintenance starts with maintaining the floor drain grating, the most obvious component of a flooring system.

A grating is a key component for a floor drain as it keeps solid debris out of the drain system. But without regular cleaning, even a fine grating may not be able to prevent contaminants such as hair and debris, which can accumulate into a mass over time.

Debris such as grease and soap harden over time, becoming solid blockage, which can be difficult to clean. When this happens, you will have to use high-powered machines such as a hydro-jet, a spinning blade or a motor-powered drain cleaning equipment.

Poor maintenance of the floor drain sump can also cause water backup. The sump is positioned under the floor drain grating. Left uncleaned, the sump can collect debris over time.

Once debris fills the sump, the exit pipe (the pipe that connects your drain system to the city connection) gets covered, which restricts water flow. The overflow that occurs over time can result in water back up from the floor drain.

In most cases where a clogged sump is the culprit, a cleanup of the sump can resolve the problem. The pipe may not be clogged in such cases. Sump cleaning does not usually require any machine. It can be performed by hand.

Schedule sump cleaning regularly. Make cleaning more often during Spring when debris such as leaves and twigs are more. Another way to keep the sump free of debris is to clean the floor drain grating and its screen periodically.

Sump Pump Issues

Sometimes, a floor drain system may necessitate the use of a sump pump. A pump is usually employed when a sufficient slope (or pitch) cannot be achieved. This slope is important to connect the floor drain to the building’s main plumbing system.

A sump pump is usually installed above the bottom region of the sump pit. Once the pit has enough water, the pump gets activated automatically and pumps away from the wastewater through a pipe so that the water does not reach the building’s foundation.

There is a check valve in the system, which stops any backflow of water into the sump pit.

As with any other plumbing equipment, there can be issues with a sump pump too. Some common damages that a sump pump is vulnerable to, include:

Mechanical Failure

The motor of the sump pump can fail due to overuse or wearing caused over time. Individual parts of a sump pump can break, which can cause the pump to fail.

Some key parts of the sump pump, which if damaged, can render the pump useless, include the impeller, driveshaft and float switch.

A Dysfunctional Float Switch

The purpose of a float switch is to trigger the sump pump when the water reaches an appropriate level in the sump pit. Afloat switch is made of lightweight material.

The switch floats upwards when the water level in the pit rises. When the specified level is reached, the pump is automatically activated. As the pump removes water and the level decreases, the float switch goes down into a depressed state, switching off the pump in the process.

The float switch could get stuck in an “off” position. As a result, the pump fails to turn on automatically even after the water level in the pit increases, leading to pump failure.

Loss of Power Source

The pump could lose its power source, possibly from a tripped circuit breaker.

Other reasons that can lead to sump pump failure and thereby drain water backup include:

A sump pump of inadequate capacity - say, your sump pit is large, and the pump is not of a capacity that matches the pit volume.

In such a situation, the pump has to work harder to remove water from such a large pit. This stress can cause the pump to wear early. Left unheeded, it can also lead to pump breakdown.

A faulty check valve - damage to the check valve (explained above) can cause pump failure and cause water backup.

A common reason for check valve failure is to wear occurring over time. Replacing the valve periodically, or as soon as damage is identified, is key to keeping the valve functional.

Sewage Backup

Floor drains are connected to the main sewer system. An overflow of this main sewer line can result in reverse water flow into the floor drain and water backup from it. Installing a sewer backwater valve can resolve the problem.

Fixing Floor Drain Water Backup

Give that there are several reasons for water backing up from floor drains, the first step is to successfully identify the source of the problem.

An experienced plumber will start with a slew of questions to understand the issue at hand. This is usually followed by an inspection of plumbing fixtures. A camera inspection may be done if the plumber has concrete reasons to believe that a sewer or drain line problem is causing the floor drain water backup.

Floor Drain Best Practices can Prevent Water Backup

Use floor drains and gratings of high quality. Steel floor drains are tough. They have a steel grating and a polypropylene frame. Cast iron drains are a good choice too.

Talk to a professional plumber to identify the right fit of drain for your needs. Ideally, a large floor drain is effective for areas that see heavy water usage.

Avoid relying on DIY methods alone. When it comes to installing, cleaning, and repairing a plumbing component, a professional can perform it faster and more efficiently.

If a plumbing issue persists even after several DIY attempts, then calling in a professional is the best solution. Persisting to work on the problem by yourself can lead to serious plumbing damages and more expensive repairs.

Regular maintenance of the drain, and other linked plumbing components, is crucial.

Clear clogs immediately. Clean the drain regularly, at least once every 4 months, using a homemade solution or a plumber-specified cleaner.

Get your entire plumbing system inspected by a plumber at least annually, or as soon as a plumbing issue arises. Regular inspection helps identify hidden issues before they cause more serious problems. 

2 Comments

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John Smith

/ January 16, 2020

Great article, useful information! Blocked drains are a pain, but should really be fixed asap.

Brodey Sheppard

/ November 18, 2019

This is a fantastic article!

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