A three-compartment sink isn’t necessary for all businesses, but when do you need a commercial three compartment sink exactly? In most, if not all states, every food service establishment must be equipped with either a two or three compartment sink.
The only time that one is not needed is when there is a functioning commercial dishwasher on the premises that can be operated.
However, in some states there entirely must be a 3 basin sink and you can only have the dishwasher if there is an audible alarm or visual verification that the unit changes cycles.
It has to indicate that is has washed, rinsed, and sanitized. It’s still recommended, even if you have the dishwasher, to have the sink as well as a backup in case anything were to happen to the dishwasher.
It’s best to check with your local state laws about the need for this type of unit as each state may be different.