Review on 🔧 White 4-Inch Oatey 43904 PVC Backwater Valve for Improved SEO by Brian Martin

This is a duct check valve. Every home needs it to keep sewage out of your bathroom/sink/toilet/drain in an emergency like a flood/hurricane or when your outdoor sewage system is repaired. If there ever is a financial crash, your sewer company will be out of a job and the sewage will eventually flow back into your home. This valve can save lives. and so incredibly easy and inexpensive. It should be "code" everywhere. Check if this is a code in your region.