How Serious Is a Slow Drain?

How Serious Is a Slow Drain?

Is it a simple clog or a collapsed sewer line?


Most of us have encountered a slow drain at some point. It usually starts as very minor occurrence. You might notice it after you wash your hands. You turn the tap off, and it takes a minute for the water at the bottom of the sink to drain out. Often, we ignore the initial signs of a slow drain because it’s not really causing any inconvenience.


But slow drain problems tend to get worse over time. It might have been hardly noticeable last month, but now you turn on the water and the sink begins to fill unexpectedly. Or you’re taking a shower when you notice you’re standing in an inch or two of water. Once you turn the taps off, the water does drain, but it takes its sweet time.


Slow drains can be a simple fix, or the sign of a more serious problem. There are a few things that homeowners can check to get an idea how serious the problem might be. First, determine if you are dealing with one slow drain—a single shower or sink—or is this happening in many or most of your drains?


A single slow drain may be a simple DIY repair. When only one drain is slow or backing up, the issue is often a clogged drain line. In the case of a bathroom sink or shower, this is often the result of hair that’s built up and caught in the line or trap. You may be able to clear the line yourself.


  • Try clearing the line using a plunger. An old-fashion sink plunger can be quite effective at pushing the clog past a bathroom sink p-trap and into the wider sewer line. A power plunger may be more effective for clogged toilets or kitchen sinks which may need the blast of pressurized water it creates to break up or dislodge the blockage and move it down the pipe.
  • Try cleaning the line using a small auger or drain snake. There are several products of different sizes and types available at most hardware stores. Some are simple barbed strips of plastic or metal that can catch on material lodged in the drain and allow you to pull it free. Others can be attached to a power drill and add a little force to the process.
  • Avoid harsh chemical drain cleaners which are toxic and can damage your plumbing. Most commercial chemical drain cleaners use hydrochloric acid as a principal ingredient. These cleaners can cause eye, nose, and skin irritation. It’s also corrosive and can eat away at plumbing pipes. There are products which can be effective on minor clogs but are still mild enough to do no harm. Both Coke and Pepsi have fairly high levels of phosphoric acid, which can break down a minor buildup clogging your drain but isn’t as harsh as commercial drain cleaner. Pour a can of warm soda into the drain and let it sit for 30 minutes, then flush with hot water.
  • If the problem persists or soon recurs, it’s time to call a plumber. A persistent or recurring slow drain can be the sign of a more serious problem and requires a professional with the expertise and equipment to troubleshoot the issue and make appropriate, lasting repairs.



Several fixtures draining slowly may the sign of a more serious problem. Your home has a series of pipes and vents that make up your plumbing drain system. Problems in the vent lines, drainpipes, main sewer line, or septic system can cause drain issues affecting your entire home.  These parts of the plumbing system can be difficult to access, making them harder to use DIY fixes. Left unrepaired, these drain issues can cause serious damage to your plumbing system and create messy backups that damage your home and your belongings.


  • Vent lines allow free air flow that equalizes the pressure in your drainpipes and main sewer line. If a vent line becomes clogged, drainage slows, and more serious problems can arise. In autumn, falling leaves and debris can clog vent pipes. In winter, heavy snow and ice can build up on the roof, blocking the vent. In spring and summer, bird sometimes build nests atop the pipe opening, blocking the vent. One symptom of a blocked vent line is a “gurgling” sound during draining.
  • Drainpipes connect your individual fixtures to your main sewer line. Drainpipes can become clogged by the same materials that can build up in sink traps and other fixtures. Hard water can create problems in galvanized steel drainpipes (found in some homes built before 1980). The limescale deposits inside these drainpipes can seriously restrict water flow over time.
  • The Main Sewer Line carries all the wastewater from your home out to the city sewer system or your septic system. Everything that goes down your drains passes through your main sewer line. So, everything that can clog those drains, can also build up and clog the main sewer line. Your sewer line is also subject to outside issues that can cause slow draining. Crushed or broken pipes, root intrusion, earth movement affecting angle or creating offsets (separations in the line) can all lead to slow draining—and worse yet, they can cause the sewer line to back up into your home. The only way to determine the health of the main sewer line is by having a camera inspection or sewer scope performed by a certified professional sewer inspector. These inspections can often find hidden problems before they create a messy backup inside your home.
  • Septic Systems are underground wastewater treatment structures often found in rural and semi-rural areas. Wastewater from your home is piped to the septic system for basic treatment. Your septic tank is a simple onsite sewage facility for your personal use. Problems with the septic system can cause waste to build up too fast for the system to handle. That waste can then back up into your main sewer line, cause slow drains inside your home. Septic systems are generally the responsibility of the homeowner to maintain, so a regular septic inspections and maintenance is advised.


A single slow drain may be a simple clog, or it may be an early warning of something more serious. Try to clear the drain as soon as you notice an issue to keep the clog from becoming a bigger problem further down the line. If you can’t clear it, don’t ignore it. Call a professional.


Multiple slow drains should never be ignored because they generally indicate a larger, more serious problem. One fairly inexpensive step to take is to have your main sewer line scoped by a certified sewer inspector. Since problems with this line can be some of the most expensive drain system issues a home can have, having yours checked will give you a good idea what you need to do to maintain it and protect your entire sewer system and keep your drains flowing freel