2019 California Standards for Accessible Design Guide (effective January 1, 2020 with July 1, 2021 amendments)

1133A.7 Knee and toe space.

Knee and toe space, when required by Section 1133A, shall comply with Section 1138A.2 and the following:

1. The knee and toe space shall be clear and unobstructed, or removable base cabinets in compliance with Section 1133A.3 shall be provided. 
2. The knee and toe space shall be 30 inches (762 mm) wide minimum, centered on the sink, countertop or appliance. 
3. A clear floor space shall not extend into the knee and toe space more than 19 inches (483 mm).

1133A.7.1 Plumbing protection.

Water supply and drain pipes under kitchen sinks shall be insulated or otherwise covered to protect against contact. There shall be no sharp or abrasive surfaces under kitchen sinks.