How to Unclog Floor Drains

Cleaning floor and basement drains

Clogged floor and basement drains pose special problems.  Access to the pipes from below is restricted. Basement drains and any drain that may flow either directly into the ground or to storm drain runoff should always have backflow prevention devices installed. Backflow prevention devices work by plugging up the drain if water starts to flow the wrong way, thus preventing water backing up and flooding your basement.

Most floor drains however will be connected to pipes carrying wastewater and sewage away from the house. When this is the case, the drain will have a trap somewhere nearby along the line. In sinks, showers and tubs the trap is just underneath, but floor drains may flow horizontally some distance before meeting the gas trap. Floor drain traps are U-shaped, with pipes flowing to and from the drain meeting the U on the sides. The U itself is capped on both ends with threaded plugs, which can be removed to provide access to the pipes surrounding the trap. Floor drain traps often have only these end-caps exposed, with the pipes running below the floor. To find the U-trap for your floor drain, look nearby for two large capped end-pipes.

You do not necessarily need to open or even locate the trap for your floor drain in order to clear a clog and restore freely flowing drainage. Follow the suggestions here to determine what is required for your situation.

Remove Standing Water

If your drain does not have a backflow prevention device, or it fell out of maintenance, and you now have standing water above the drain, we recommend you read more about sewer and storm drain backups, backflows, and floods, because the standing water must be removed to safely address the clogged drain. Flooding not only damages property, but poses a health risk as well. Standing water can be siphoned away, but only if you can reach a hose from the flood to somewhere lower than the flood, usually you will need some sort of pump to mechanically move the water somewhere else. An inexpensive electric submersible pump will drain the water so you can reach your belongings and the clogged drain.

Safety Considerations

Liquid drain cleaner is not recommended. Liquid drain cleaner rarely works, and only makes things more toxic and difficult to deal with.  In the case of clogged floor and basement drains in particular the clog--often household debris or even tree roots invading damaged pipes--won’t even be affected at all by the cleaner. And that is only if you even get the dangerous chemical to the point of the problem. So don’t use liquid drain cleaner. If you have already applied liquid drain cleaner or bleach, you must be very careful going forward. Wear old clothing, rubber gloves, and protective eyewear. Keep the area ventilated, and keep anybody else working there aware of the hazard.

If there is even a small amount of standing water remaining, do not use any electrical equipment not approved for wet conditions.

Clearing the Drain

Once any standing water has been removed, you can now deal with cleaning the drain itself. Have a bucket or trash basket ready to hold any water-soaked debris you can pull out of the drain. Rubber gloves can help you keep a strong stomach. Gather any debris or garbage above and surrounding the drain, and get it out of the way.

Consult your backflow prevention device owner’s manual for recommended procedure for proper maintenance, and how to open up the drain for cleaning. If you’re dealing with a straining metal screen, assess whether you can remove the clog without removing the screen.Backflow prevention devices are perfect for when there is any possibility of water backing up the drainpipes and flooding the area, but your drain may have only a strainer in place, or nothing at all. If the hole is not covered with at least a strainer to keep out objects larger than a grape, then things will just fall in there and clog it up again, so find or replace the strainer.

Locate the Problem

Peer into the drain, shining a flashlight or bright light from above. If you can see the obstruction, determine its composition. Clogs composed of hair or grease can be busted up and pulled out a bit at a time with a carefully fashioned bent coat hanger.   Other obstructions, such as plastic lids or objects that may have slipped through the strainer, will be tougher to remove unless you first remove the screen.

Usually the straining screens are held on with two or three screws. You must be very careful not to drop the screws down the drain! This is why we suggest exploring the clog with a wire through the screen first, because you don’t want a screw falling into the drain while you are removing or replacing the straining plate. Have somewhere ready to safely place your screws or other parts while you clear the drain. If you have a screwdriver that is magnetized, this is a good time to use it, but only remove the screws if the obstruction cannot be pulled back out without doing so.

You can try the plunger and even some smaller handheld drain augers without removing most straining plates for floor drains. If you have located the U-trap in the floor associated with the troublesome drain, it should be easier and safer to access the pipes by opening up a capped end of the trap.

Use caution as you break the seal around the drain to avoid any backsplash. Check to see if the water has flowed away. You should try the plunger several times, adding water to the drain as needed, to see if you can eventually break the clog apart. If you feel you are making progress, allow the clog to soak in a squirt of dishwashing liquid. This can cause greasy buildups to soften and decompose as well as encourage clogged bits to flow more smoothly. A strong soapy solution allowed to soak through the blockage for several hours can potentially soften the clog considerably for busting apart with the plunger.

When a Plunger is Not Enough

If free flow has still not been restored, or you suspect the obstruction is a solid object that must be extracted, then it is time to consider consulting a professional. A drain cleaning service could quickly determine the problem and suggest a solution. It may be that tree roots have grown into your drain pipes, and need to be removed for restored flow, or the pipes may have become separated at an underground joint over time. A professional would have the expertise and the tools, such as a pipe crawling camera and mechanized plumber’s snake, to get the job done properly.

However, if you are a determined do-it-yourself homeowner, there are still more options.

If you can locate the trap for your floor drain, now is the time to look inside. Use large slip-joint pliers to grasp the square protrusion of the cap, and rotate counter-clockwise to unscrew the plug from the pipe. Opening one or both ends will provide access to the most likely location of the clog; inside or on either side of the gas trap. This is another job for rubber gloves and a strong stiff wire.

Drain Augers and Plumber's Snakes

Slowly draining or completely blocked floor drains where the obstruction is within a several meters of the drain can be dealt with using a handheld or electric drain auger . These are long, stiff metal cables with hooked, weighted ends, which can be threaded into pipes cleaning and clearing a new path through nearly anything.

You should work the auger on the length of pipe between the drain and the trap, from either end, and also down the pipe leading away from the trap. Feed the auger cable into the pipe. Work it back and forth, scraping the sides of the pipe clean as you go and, importantly, spinning the cable round and round to screw it farther down the drain.   You can work around tight corners if you keep spinning the cable as you feed it into the pipe.

Busting Clogs with an Auger

You may be able to feel the obstruction when the auger cable tip meets it. Try to determine again if the clog is fibrous or solid. If it can be busted apart or feels soft, working the auger back and forth, spinning in both directions, should break it into small enough bits to flow away. A garden hose providing strong flow down the drain is helpful to carry away the debris as you bust up the clog, but keep in mind the precautions mentioned above. If you sense that the obstruction is not soft but solid, you should instead attempt to screw the auger just around and past the clog, and then reverse the process, removing the cable, hooking the object and bringing it back up the pipe along with it, until you can remove the foreign object from the drain altogether. When using an auger, screw in the same direction when inserting and removing the cable. 

Consult Knowledgable Authorities

If you believe the obstruction to be located downstream of both your drain and trap, and perhaps even out of the reach of a handheld auger cable, you should now consult with your municipality concerning proper procedure. People from the city, county, or other entity delivering your sewer and wastewater service will come and assess the problem, usually for free. If they determine the problem to be in their pipes, they will pay to get things fixed and could even cover some property damages.

More often, though, they will find the trouble to be between the house and the main lines. When this is the case, it is the responsibility of the homeowner or landlord to keep all pipes from the house to the municipal line in working order. Check your sewer or water bill for the number to call about your concerns.

Rinsing Pipes Free of Residue and Buildup

Once you have freed the drain of clogs, flush the pipes thoroughly with plenty of water. Hot water and a small amount of liquid dishwashing soap will cut through much of any greasy buildup on the walls of the pipes, but liberal amounts of running room-temperature water is still very helpful. You must at the very least flush enough water down the pipes to re-establish the water seal against sewer gases in the U-trap.

Floor drains are notorious for odors such as those caused by mildew, mold, decomposition, or bacteria, which can develop between drain and trap. Pour a half a cup of baking soda down the drain followed by a quart of white vinegar a few times a year for an inexpensive way to remove and prevent those stinks.

Sewage odors could indicate a leaking or empty gas trap. If you smell sewage from a dry drain, you could try a gallon of water to refill the thirsty U-trap and block the gases from entering the basement or bathroom. If the odor persists, find the trap and examine it for leaks and proper working condition. A damaged or cracked pipe should be handled by a licensed plumber.

Keep Up the Good Work

Maintenance is important to keep any drain freely flowing, but with floor drains in particular it is important to keep on top of the job, because a basement drain failure can mean the destruction of property from flooding. One way to be sure your home is always as safe as possible is to include checking floor drains in your routine of checking smoke detector batteries. You should check your smoke detectors and your flood drains at least a couple times a year to see they are functioning properly. And if the drain flows directly into the ground, or is connected to storm runoffs, or is below ground level, a backflow prevention device is advisable.