Does A Basement Floor Drain Need A Trap?

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While often overlooked, your basement floor drain is one of the most important parts of the plumbing system in your home. It keeps your basement floor dry and protects your home from flooding. But do basement floor drains need traps like drains in other areas of the home? We've consulted with the experts to give you the right answer to this question.

Yes, a basement floor drain does need a trap. Traps keep sewer gases and odors from entering your home and posing threats to your health. Building codes often require floor drains to have traps, and most floor drains have built-in traps.

With that query answered, you may have a few more questions about basement floor drain systems. Keep reading to find out how basement floor drains work, what a trap does, and how to fix issues with your drain.

Empty interior of a living room with wooden vinyl tiled flooring, gray walls and recessed lighting, Does A Basement Floor Drain Need A Trap?

Why is a basement floor drain trap important?

Also known as a P-trap, a floor drain trap creates a water seal that keeps sewer gases and odors from entering the home. Without this fitting, sewer gas can emit into your home. Not only does this release a strong odor that makes your surroundings unpleasant, but it can also compromise your and your family's health.

Your trap should always be filled with water. Otherwise, the liquid from it will evaporate and it won't be able to do its job. Some traps are filled manually, while others have a trap primer that automatically adds water to the P-trap to create a water seal.

A leak in the basement floor due to heavy rain

How do I fill my basement floor trap?

A nasty sewage smell in your basement is a telltale sign that your floor drain trap needs water. All you have to do is pour water down the drain to refill it. Two to five gallons should be enough to fill it and ensure it goes back to blocking away sewer gases from your home.

If your basement floor drain doesn't get much use, your trap will dry out eventually. Make sure to pour water down your drain at least once a month to keep this from happening.

A good tip to keep the water in your trap from drying out is to pour a little oil into it. The oil will halt evaporation and keep your trap wet. Mineral oil is ideal for this hack.

How do basement floor drains work?

Your basement floor drain is located at the lowest point of the floor. It's designed to collect water - whether from water heater leaks, rain, or condensation from HVAC systems - and lead it away from the house. Older floor drains may carry the water to a drainage ditch to keep excess water away from the septic tank.

Basement floor drains are vital to the plumbing in your basement, especially since most homeowners do their laundry and keep sinks and water heaters in that part of the house. It prevents water damage from wreaking havoc on your home, keeps your floors dry, and protects your basement from mold.

Water leak in the basement

Where does the drain on the basement floor go?

Some basement floor drains connect directly to the home's sewer system, which means they can drain washing machines and water softeners. They can also drain basement laundry sinks. Floor drains connected to the sewer system often suffer from backflow, which is typically the result of blocked or overloaded pipes. Backwater valves are the solution to this common problem.

Other basement floor drains connect to a sump pit, which is a hole dug into your basement floor. It's set in a deep position to collect water and prevent it from staying in the pipes. A sump pump then lifts the water into a draining space. In this case, local ordinances may not permit the draining of water with detergent or chemicals.

A blue tiled floor inside a basement bathroom

In some cases, the basement floor is situated below the spot where the main sewer line leaves the home. Here, the drain connects to a sewer pit with an ejection pump. For this type of connection, it is acceptable to drain a sink or a washing machine. This is the type of connection newer homes typically have.

How do I fix a clogged basement floor drain?

Another common problem with basement floor drains is clogging. This is because dirt, grease, lint, soap scum, hair, and other debris can build up over time and block your drain. Clogged drains can lead to foul odors and flooding. The good news is there are many solutions to successfully unclog your drain.

Use a plunger

You can solve minor blockages easily with a plunger. Simply cover the drain with the plunger and pump a few times. A good tip is to put petroleum jelly on the edge of the plunger to improve the suction.

Mix baking soda and vinegar

This classic declogging method is popular for its effectiveness and easy-to-access ingredients. Here are the steps for unblocking your floor drain with baking soda and vinegar:

What You'll Need

  • Baking soda
  • Vinegar
  • Pot of hot water
  • Screwdriver
  • Gloves

  1. Remove the drain cover with a screwdriver.
  2. Put on your gloves and scoop out as much buildup as you can.
  3. Pour a pot of hot water down the drain. Leave to soak for ten to 20 minutes.
  4. After soaking, pour a box of baking soda followed by a 32-ounce bottle of vinegar into the drain. Leave to soak for another 10 minutes.
  5. Pour in hot water once again.

Snake the drain

Now if the two other methods fail, it may be time to snake the drain. Don't worry; you can do this on your own with the right tools and guidelines. Here are the steps you can follow to snake your basement floor drain:

What You'll Need

  • Drain snake or plumber's auger
  • Screwdriver
  • Chisel
  • Pipe wrench
  • Hammer
  • Shop vacuum
  • Teflon tape

  1. Remove the drain cover with a chisel or screwdriver.
  2. Clean the trap out with your shop vacuum.
  3. Take off the cap from the clean-out plug manually or with a chisel.
  4. Insert the drain snake or plumber's auger tip into the pipe.
  5. Keep pushing it in until you feel resistance which indicates you've found the clog.
  6. Reel the snake back and lift the gunk and debris off the cable.
  7. Wrap Teflon tape around the clean-out plug before putting it back in for easier access in the future.
  8. Put the clean-out plug back into place.
  9. Pour water into your drain to see if it's unclogged.

Learn more about solutions to basement clogs by reading this instructive guide: "How To Unclog A Basement Drain."

Does a basement floor drain need a vent?

Building codes in states like New York City don't require floor drain vents. The building code states unless it's more than 15 feet from the vented line where it connects:

"No vents will be required for piping serving floor drains when the floor drain is located not more than 15 feet (4572 mm) from the vented line to which it connects."

Building codes in other states such as Illinois require vented floor drains, however. The building code states:

"Any building or structure in which plumbing fixtures or piping is installed in or under a concrete floor to accommodate fixtures on the level of the concrete floor shall have at least one trapped and vented floor drain."

To be sure of your state's ordinances about this matter, make sure to check your local building codes.

For more information about building codes for basements, take a look at this article: "Does A Basement Bathroom Need A Window?"

In Closing

Interior of an empty white walled basement

Basement floor drains have traps that keep sewer gases from escaping into your home. This trap should always be filled with water so it can create a water seal that protects your home against nasty odors and hazardous emissions. This way, your basement will continue to serve its function in your home without hassle.

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