flushing a toilet that won't drain

“Help! My Toilet Flushes But Doesn’t Drain!”

A toilet that flushes but doesn’t drain is typically caused by one of three possible problems. Here’s what you need to know about this common issue.

Toilet Troubleshooting Tips

When pulling the lever, you’ll notice that water rushes in the bowl as usual. However, instead of draining, the water level in the toilet bowl rises higher to where it was prior to flushing. This is distinct from cases where the toilet simply doesn’t flush.

Here’s what causes this to happen:

  • Clogged toilet. The most common cause of a toilet that doesn’t drain properly is simply that it’s clogged, which itself can happen for any number of reasons. Typically, using a plunger is enough to dislodge the clog and allow the water to drain properly. If that doesn’t work, you may be dealing with a different issue.

  • Venting issues. Air pressure plays a crucial role in most plumbing systems. When everything is working, vents will apply downward pressure to ensure waste water flows out of your plumbing system and toward municipal lines. A problem with the venting will therefore translate to problems with your plumbing.

    A telltale sign that your issues are caused by inadequate air pressure in the plumbing is if the water in the toilet bowl continuously rises and falls, even when not in use.

    In a new construction, venting problems are often caused by a vent cap that was mistakenly left in place. If your home is older, chances are there’s something more serious going on.

  • Obstructed drain line. Sometimes a toilet won’t drain because there’s a blockage in the room’s branch line or in the building’s main drain line. This, however, is fairly easy to recognize, because the toilet won’t be the only fixture affected. In the case of a clog in the branch line, the sink, bathtub and shower will also drain slowly. In the case of a blockage in the main drain line, you’re likely to see slow drains throughout the building. This can be caused by any number of things, from grease building up in the pipes to tree roots infiltrating the drain. You’ll likely need an inspection to determine the exact cause.


Our Licensed Plumbers Are Ready to Take your Call!

If you’re dealing with a persistent toilet or drain problem, your best bet is to contact a local licensed plumber. Modern Air & Water provides plumbing services throughout the Edmonton area and has the tools to non-invasively inspect your pipes. Contact us today to schedule an appointment or get a free estimate!