Which type of standpipe system does not have a permanent water supply?

The type of standpipe system that does not have a permanent water supply is the manual dry standpipe system. This system is designed to be used in conjunction with a fire department's water supply, requiring firefighters to bring the necessary water to the system when needed. In this setup, the standpipe is typically kept dry, and the firefighters are responsible for connecting hoses and supplying water from external sources.

This distinguishes it from other types of standpipe systems. For instance, an automatic wet standpipe system is always filled with water and is designed to provide immediate fire protection without the need for any external connections. An automatic dry standpipe, while also not having a permanent water supply, is designed to fill with water automatically when activated, which means it does not require manual intervention. A manual wet standpipe, on the other hand, maintains a constant supply of water and can be used directly without needing additional water source connections.

Thus, the manual dry standpipe is specifically structured to rely on external water sources and does not maintain a permanent water supply, making it the correct answer among the options provided.