Why is my basement floor drain backing up?

Where does a basement floor drain actually go?

A floor drain is a simple thing: a grate over a trap, connected to the main drain under the floor. Because it sits at the lowest point in the house, it is the first place wastewater appears when the main line cannot carry it away. In many Philadelphia rowhomes, the floor drain ties in just upstream of the house trap, the U-shaped fitting near the front wall that every drop of wastewater passes through on its way to the lateral and the street sewer.

Some floor drains do not connect to the sewer at all. In parts of Lower Bucks, a floor drain may run to a sump pit or to a dry well. Knowing which kind you have matters, because a sump-connected drain backs up for entirely different reasons than a sewer-connected one. If you are not sure, run water into it and listen for where it goes, or ask us to trace it during a camera inspection.

What is making it back up?

Water coming up through the grate has one of a few causes, and the timing tells you a lot:

• It backs up when you run water inside (laundry, shower, dishwasher): the main drain or lateral is blocked downstream. Grease, roots, wipes, or a full house trap are the usual reasons.
• It backs up during or right after heavy rain, whether or not you are using water: the combined sewer in the street is surcharging, and water is pushing back up your lateral. Your pipe may be fine.
• It backs up only when the washer drains: a partial blockage that cannot handle the washer's fast discharge.
• It smells but never backs up: the trap has dried out and sewer gas is coming through. Pour a bucket of water in and the smell should stop.
• Clear water is usually rain or groundwater. Gray or brown water with paper is sewage from your own fixtures. Water with grit and street debris came from the public sewer.

Is it my pipe or the city's sewer?

This is the question that decides who fixes it. In Philadelphia, the property owner is generally responsible for the lateral from the house to the street main, including the house trap and curb trap. If your lateral is blocked or broken, it is your repair, and PWD may issue a Notice of Defect if they find the defect from their side. If the public main is surcharging in a storm, the pipe itself is not at fault, though there are ways to protect the basement.

The clues: backups only during storms, neighbors on the block having the same problem, and clear water rather than sewage all point toward surcharge. Backups on dry days when you run water, and a cable or camera that finds a blockage inside your lateral, point toward your pipe. Sometimes both are true; a partly blocked lateral floods faster in a storm. Confirm current responsibility rules with PWD, or with BCWSA or Aqua Pennsylvania in Bucks County, since the lines differ by utility.

What do we do about it?

We start at the cleanout or house trap, because that is where the main line can be reached without pulling a fixture. A cable clears the immediate blockage. Then the camera goes in, and that is where the real answer comes from: roots at the joints, a grease-lined cast-iron main, a house trap packed with debris, a belly holding water, or a cracked or collapsed section of clay.

From there you get options, laid out before any work starts:

• Cleaning alone, with a maintenance interval if roots or grease are the cause.
• Hydro jetting when the pipe walls are coated and the camera shows the pipe can take it.
• Repairing or replacing the house trap or a failed section, with our own underground crews doing the excavation.
• A backwater valve on the main drain for homes that flood from sewer surcharge in storms. Philadelphia L&I and your township have permit and inspection requirements for this work; confirm current requirements.

What affects the estimate?

Two floor-drain backups can look identical from the basement and need very different work. The drivers on the estimate are whether the fix is cleaning or repair; how deep the lateral runs and how long it is; what is on top of it (basement floor, sidewalk, street); the pipe material; whether a house trap or curb trap needs replacing; permit and inspection requirements; and surface restoration afterward. For Philadelphia homeowners facing a lateral repair, check current PWD programs, including the Homeowners Emergency Loan Program (HELP), since eligibility rules change. 0% financing available with approved credit (Wisetack).

What should I do now?

If water is coming up, stop using water in the house and keep people and pets out of the basement until it is cleaned up. Note the time, the weather, and what was running. Those three details usually tell us which cause we are looking at before we even arrive.

Then request service. We will clear the line, camera it, and show you what is going on under the floor before we recommend anything. If another company has already quoted a lateral replacement, we offer a free second opinion on qualifying larger projects.