What is the smallest size cold potable water supply line that can serve a kitchen type sink?

For a kitchen sink that requires a cold potable water supply, the appropriate size for the supply line is critical to ensure adequate flow and pressure. The smallest acceptable size for a cold water supply line serving a kitchen sink is 1/2 inch.

A 1/2 inch diameter line provides sufficient flow capacity to meet the demands of typical kitchen fixtures, including faucets and other appliances that may be used in conjunction. Smaller diameter lines, such as 1/4 inch or 3/8 inch, may not provide enough water flow for the kitchen sink, particularly when multiple fixtures are used simultaneously or when high flow rates are required.

A 3/4 inch line is larger than needed for a single kitchen sink and may lead to unnecessary material costs and could also complicate connections with standard fixtures, which are typically designed for 1/2 inch supply lines.

Overall, using a 1/2 inch supply line is the standard practice for achieving the necessary performance and reliability in a kitchen sink installation.