Sink Backing Up into a tub: Causes & Solutions


Although it can be quite disgusting, it is not uncommon for a bathroom sink to drain into the bathtub. This can make showering quite impossible and it is a problem that needs to be dealt with as soon as possible.

This is normally a sign that sediments have settled on the P-trap that is located on the bathtub clogging the drain. However the tub trap is clear if the tub backs up when water is poured down the sink. This means that there is a clog but it is past where the tub and sink drains merge. This can be caused by a number of things such as hair, soap scum, and other debris.

Signs of Backup

When the sewer has been plugged, or your septic tank needs some pumping some of the things that can happen include:

  • Water backs out of the tub drain when the toilet is flushed.
  •  When the bathtub has been emptied, the water stops flowing and then it bubbles back into the toilet.
  •  When the kitchen sink is emptied, the water from the sink backs up to the toilet.
  •  When the toilet is flushed, sewer water normally backs up through a downspout, driveway drain, patio drain, or the lowest floor drain in the home.
  •  When a load of laundry is run, soapy water normally comes into the shower, floor drain or shower.


There are a number of solutions you can try out and some of them include:

  • Plunging the tub- this should be done after you have filled the tub with at least 2 inches of water. Fit the plunger around the tub train in a bid to make an airtight seal and pump it several times until you see it is working.
  •  Use a bladder or auger- these are great for cleaning out clogs, use an auger or inflatable bladder by connecting it to your garden hose and inserting it into your drain.
  •  Use drain cleaners- although this may work effectively it is important to make sure you use it carefully as they can also damage your pipes.

Making sure the clog is gone ensures you can enjoy your bath time without any problems. You can do it on your own, but if it does not work call in a professional plumber to help.