What should be installed in the house drain if there is a danger of backflow of sewage?

The installation of a combination backwater valve with a manually operated gate valve is particularly effective in situations where there is a risk of sewage backflow. The backwater valve is designed to prevent the reverse flow of waste and sewage into the home, usually caused by flooding in the public sewer system. This valve opens to allow waste to flow out but closes tightly to block any backflow, protecting the home from potential sewage contamination.

The addition of a manually operated gate valve provides an extra layer of protection, allowing for manual intervention when necessary. For instance, if significant rainfall is predicted and the risk of backup is high, homeowners can close the gate valve to reinforce the backwater valve's function, further preventing any sewage from entering the home. This dual protection is essential in areas prone to flooding or where the sewer system is inadequate to handle heavy storms.

In contrast, the other options either do not address backflow effectively on their own or do not serve the specific function of preventing sewage backflow. A standard gate valve, while useful for controlling water flow, does not provide the same protection against backflow as a combination valve setup. Similarly, a sump pump is designed to remove water accumulation from areas like basements and does not serve to block sewage from flowing back