Toilets Backup into The Kitchen Sinks: Causes and Solutions

A toilet backing up into the kitchen sink is not an unusual problem. In fact, most American homes with kitchens close to the toilets often complain about this problem. You can fix this problem by either hiring a plumber to help you or alternatively, solve it on your own.

Why Toilets Backup into Kitchen Sinks

For a toilet to backup into the kitchen sink, there must be an obstacle blocking the toilet’s waste line, and also the sink must be connected to that waste line. Also, the obstacle causing the blockage must be in the sink’s downstream. As more water rushes through the blocked waste pipe and meets the obstacle, it pushes a lot of air through the sink’s vent and fills the pipe with water forcing the water to enter the kitchen’s sink drain. At the same time, the toilet begins backing up. Since the diameter of the kitchen sink is much smaller diameter compared to the diameter of the toilet’s drain, water tends to rise to higher levels in the kitchen sink drain than it does in the toilet pipe. And, even though the kitchen sink might be on higher ground than the toilet, water still overflows in the kitchen sink.


  1. Plunge with caution.

Before pulling out your plunger to remove the blockage, consider the physics behind what you are trying to do. By applying a lot of force while plunging the toilet, however it fails to clear the blockage, the plunger might force more water and air into the kitchen sink resulting in a mess. Before plunging, it’s advisable to plug the kitchen sink using a stopper to block the sink’s overflow holes. This makes the entire process more effective as there will be only a few avenues for water and air to escape therefore exerting more pressure into the waste line to clear the obstacle.

  1. Snaking the clog.

If plunging fails to clear the blockage, although it’s very unlikely; an alternative solution for the problem is using the toilet snake or a closet auger. Slowly fit the auger’s head through the toilet drain, and when you start feeling some resistance, crank the auger’s handle with more force to work it into the obstacle. You will know you have succeeded when water starts draining thorough the toilet and kitchen sink. It’s good to let water flow through the sink for some time to clear and clean your sink and the waste line.

Toilet backing up into kitchen sinks is not a good site to see, neither is it healthy. Therefore, it needs to be done with utmost care and caution. You can solve the problem by yourself using the above solutions or hire a professional to do it for