The connection between a washer drain hose and a standpipe must be?

The connection between a washer drain hose and a standpipe must be non-airtight to allow for proper drainage and venting of the system. This design helps prevent siphoning, which can occur if a hose is connected in an airtight manner.

In a non-airtight connection, the washer drain hose can freely move and also allows air to enter the pipe system, which helps maintain an equilibrium of air pressure. This is crucial because it ensures that water can drain effectively without creating a vacuum that might impede flow.

Additionally, a non-airtight connection helps reduce the potential for sewer gases to enter the home. The configuration allows for proper drainage while also protecting against foul odors that could back-siphon into the washing machine.

While securely fastening the connection (as suggested in one of the other options) is essential for stability, it does not specifically address the need for air circulation in the drainage system. Similarly, having an airtight connection would lead to drainage problems, and positioning it above the flood level is important but unnecessary if the connection itself doesn’t allow for proper function. Thus, ensuring that the connection is non-airtight is vital for a functional and safe plumbing system in relation to washing machines.