One of the most common defects at old Minneapolis and Saint Paul houses is a missing cleanout plug in the floor drain. When we find this during a Truth In Sale of Housing Evaluation in Minneapolis, it’s actually a required repair item. A missing cleanout plug can allow hazardous sewer gas into the home and often indicates a clogged floor drain. To learn why and how, read on.
Every plumbing fixture has a trap. A plumbing trap prevents foul-smelling sewer gas from entering a home. The image below shows a P-trap, which can be found at sinks, showers, and bathtubs.
The left side of the trap connects to the plumbing fixture, and the right side connects to the sewer. The ‘sewer’ side will have sewer gases present, but the water at the bottom of the trap prevents sewer gases from entering the building.
Floor drains are no exception. The photo below shows a floor drain viewed from the side.
The shaded portion shows the trap where water will always sit, which prevents sewer gas from entering the building. When you look at an installed floor drain, all that you typically see is the grill on top; the rest of the drain is always buried in the basement floor.
What if the drain is clogged?
Floor drains clogs happen in two places; one is the trap itself, and the other is a clog in the line downstream from the drain. To know the difference, try removing the cleanout plug; it’s that thing I circled in the photo below.
This will allow water to drain past the trap, through the area highlighted below.
If you remove this plug and water drains properly, you have a problem with the trap, and your best bet is to use a drain auger to clean out the trap. As long as someone didn’t pour concrete or tile grout down the drain, it shouldn’t be a big deal to fix this. If you remove the cleanout plug and water still doesn’t drain, you have a problem with the drain line downstream from the trap. Try using a drain auger to clean out the line by pushing it through the cleanout hole.
When this plug is removed, however, sewer gas will enter the building. After you’ve cleaned the drain, be sure to put the cleanout plug back into place. You don’t want stinky sewer gas coming into your home.
What if the cleanout plug is missing?
If you have an existing floor drain with a missing cleanout plug, it usually means one of two things:
- The drain was clogged, someone removed the cleanout plug to clean the drain, and they forgot to replace the plug.
- The bottom of the trap is clogged, and someone removed the cleanout plug to allow water to drain directly into the sewer, instead of going through the trap.
To know the difference, take a look at the water level. If the water is right at the cleanout hole, you have a clogged trap that needs service. If the water level is a couple of inches below the cleanout hole, you should be fine. All you need to do is replace the cleanout plug.
On some older floor drains, the threads that used to accept a cleanout plug are damaged or badly rusted, so it’s impossible to screw in a new cleanout plug. The right way to fix this is to install a rubber plug. One type of plug is a piece of rubber sandwiched between two pieces of metal that expand the rubber when tightened together. The two photos below show a rubber plug before it’s tightened and after it’s tightened.
Another type of rubber plug can be found at Real-Tite Plugs – a company located in Golden Valley.
When the cleanout plug is missing it needs to be replaced, and the floor drain may need to be cleaned out or replaced. If the drain cannot be cleaned, the entire floor drain needs to be replaced.
