What to Know About Your Basement Floor Drain

Basement floor drain with tile
Andreas Schlegel / Getty Images

Keeping your basement floor dry is the first step to keeping your entire basement dry. If you want to turn your basement into a second living area, a home theater, a bedroom for a family member, or even a full-scale apartment to rent out, the basement must be perfectly dry.

Installing a basement floor drain or maintaining an existing drain is vital to accomplishing these projects and to keeping your entire house in good shape.

What a Basement Floor Drain Is

A basement drain is installed in a concrete floor, usually when the home was originally built but sometimes retroactively. The drain moves water from one section of the basement to the outside of the house.

The drain is usually in a utility area where the water heater, furnace, or laundry room are located or in any area where moisture is prevalent.

The floor is sloped so that water will move toward the drain. The floor can remain as concrete or the concrete can be tiled over. In most cases, the floor is hardscaped with a waterproof or water-resistant material capable of drying out rapidly. Whatever the floor covering, the floor still must maintain the same slope.

Why a Basement Floor Drain Is So Important

  • Meets code for most new construction

  • Moves water out of basement entirely

  • Central collection point for all leaks within basement

  • Retroactive installation is messy and expensive

  • Will not solve all of your basement moisture issues

  • Blocked drain can create even greater problems

In any part of the home other than the basement, internal flooding water (such as that from a dishwasher or broken pipe) has somewhere to go: either laterally or down. Flooding water is a huge mess, but not as disastrous as it could be because the water does have an escape route.

In a basement, the water has nowhere to go. With concrete walls and earth on all sides, a full basement is a basin. In the event of flooding, the water will rise and can potentially fill the entire basement until it reaches an escape route such as a basement window or ground-level.

Basements are water-prone both from internal sources (pipes, washing machines, water heaters) and from exterior sources, such as groundwater runoff. A basement drain captures water and drains it off long before it has time to build up and damage the basement.

How a Basement Drain Works

The basement drain is located at the lowest point of the basement floor. Water leakage moves by gravity to the drain.

The drain always has a protective grill that can be removed. Below the grill, embedded in the concrete, is a circular drain unit that contains a P-trap and a cleanout.

Water moves out of the drain and downslope through a pipe. Finally, the water exits the home either through the sewer or into the sump pump collection pit, where it is pumped upward and out of the house.

What Causes a Smelly or Clogged Basement Drain

A basement drain that smells like sewer gas usually means that the basement drain trap is dry. Water is supposed to always remain at the bottom of the trap—the same as with all other drain traps in your home. When the trap is dry, sewer gases flow from the outside to the inside of your home.

The most common cause of a blocked basement drain is debris from the basement floor that ends up in the drain. Because the floor drain slowly collects dirt, hair, and other debris over time, this matter can build up to form a clog that prevents water from moving out.

Fixing a Smelly or Clogged Basement Drain

Smelly Basement Drain

The best way to fix a smelly basement drain is to reload the trap with water.

Fill a five-gallon bucket with about four gallons of water. Carefully pour the water into the basement drain. The water should all flow through and out the drain pipe. The remaining water will stay in the trap and block odors from entering the basement.

Clogged Basement Drain

  • Plunger: Vigorously plunge the drain and trap several times with a bell-shaped toilet plunger.
  • Baking soda and vinegar: Shake a half box of baking soda into the drain, followed by two cups of white vinegar. Let the mixture foam up. Follow with boiling water to clear out the drain.
  • Snake the drain: Use a hand-held drain snake or auger (not a machine) to clear the drain. Remove the drain grill. Push the end of the snake into the drain while continuously rotating it. When the snake hits the end, stop rotating. Slowly pull back the snake and remove the debris from the end.
Article Sources
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  1. What's that stink? It could be your drain. Environmental Health and Safety Chemical Safety. Michigan State University. 2020.