Individuals looking to upgrade their existing kitchen sinks are increasingly looking for big, deep and highly functional designs, it has been claimed.According to Jennifer Sheffield, showroom manager of Plumbing Unique, consumers are being swayed by the commercial look - like something a celebrity chef might have.Speaking to the Sacramento Bee newspaper, Ms Sheffield cited a recent study by Kitchen Bath Design News which found that stainless-steel kitchen sinks still lead the marketplace.The long-lasting nature of the material added to their ability to effortlessly fit in with all sorts of kitchen designs makes them a popular choice with those looking to upgrade their rooms.However, the expert also suggested that copper was becoming a more popular material for kitchen sinks.Were definitely seeing more copper in the kitchen, Ms Sheffield told the news provider. Copper is antibacterial by nature. It goes with a Spanish hacienda or a rustic Tahoe cabin. Copper can also look very modern.