4 Pcs Drain Backflow Preventer,One Way Valve,Waterless Trap Seal, Adjustable Sink Anti-Clogging Silicone Floor Drain Cover for Pipes Tubes in Toilet Bathroom Kitchen (Blue

Water went everywhere

The main purpose of this is to allow water through but not to be able to back up. As you can see, the drain in this tub is broken and water has been getting around the bottom drain under the house and soaking through the installation which is why I got these until I get a chance to replace the drain. It works pretty well for this purpose but does not stay in place without some plumbers putty and unfortunately water drains very slowly through this. It's OK and working for the most part for my purpose but I wouldn't recommend.

We have an older 80s home, and there is a floor drain in one room. The drain has often smelled like sewer. We suspect it was installed without a trap. We recently added this by simply inserting it into the drain. Since installing it, ALL the smell is gone. I am so happy for this simple solution for an issue that has annoyed us a long time and potentially reduced indoor air quality. Before tearing out your drain, give this a shot if it smells. These are cheap enough to at least try it in my opinion.