Which type of water supply system is mandated by the code for residential buildings?

The National Plumbing Code of Canada mandates the use of a potable water supply system for residential buildings to ensure the safety and health of occupants. A potable water supply system delivers water that is safe for drinking, cooking, and sanitation, meeting specific quality standards set forth in the code.

This requirement is crucial as residential buildings serve as primary living spaces where individuals require access to clean and safe water for daily activities. By specifying a potable system, the code aims to protect public health by preventing waterborne diseases and other health risks associated with contaminated water sources.

The other options, while they may serve specific purposes in certain contexts, do not fulfill the essential requirement for residential water supply. Non-potable water systems are typically used for irrigation or flushing toilets but not for drinking. Saline water supply systems are generally unsuitable for any domestic applications due to high salinity levels that render the water unsafe for consumption. Recycled water systems, while used for irrigation or non-potable purposes, are not typically mandated for residential dwellings where potable water is necessary for everyday use. Thus, a potable water supply system is the only suitable choice under the code for residential buildings.