If you were presented a stainless steel item and a plastic item, which would you perceive as superior? This is a common divergence in the business end of bidets that consumers are presented with while shopping.
There are a variety of materials that brands can use to manufacture a bidet sprayer. You may see plastic, aluminum coated plastic, stainless steel coated plastic, and stainless steel. While one may think that stainless steel is inherently better than the competitors, you will not notice a difference in the wash produced by one or the other. However, it is undisputed that stainless steel dominates in the areas of build quality and hygiene.
Functionality
While some sommeliers can blindly discern the difference between a ten year wine and an eleven year wine, nobody can blindly use a bidet and know what material the nozzle is made of. This is because the wash itself is determined by the water that produces it and its many characteristics. These include spray pressure and pattern, and water temperature and aeration.
Hygiene
Regardless of materials, all electronic, and some mechanical bidet seats have a self cleaning nozzle that rinses itself between uses. The stream of water that washes over the nozzle as it retracts into its housing washes away nearly all debris. Unlike materials such as plastic and aluminum, the rigidity and structure of stainless steel makes it absent of pores and difficult to crack or scratch. Without these spaces to harbor dirt and bacteria, both self and manual cleaning of stainless steel is all the more effective, and caretakers do not have to be particularly gentle when wiping its surface. This explains the prevalence of stainless steel in sterile settings such as food service and healthcare, where germs are minimized. While plastic is not as inherently tough as stainless steel, most plastics used in bidet nozzles are sealed to reduce the potential for scratches, pores, and cracks.
Quality
You will see nearly all higher-tier bidet seats incorporate stainless steel nozzles, and that is to be expected with their higher price tags. Examples include the Bio Bidet BB-2000, the Brondell Swash 1400, and even the $300 Bio Bidet Slim Two. It may appear that stainless steel is the way to go, that is until we look at Toto Washlets.
Toto Washlets are viewed as the pinnacle of bidets, yet not one of their nozzles is stainless steel, not even the $13000 Neorest NX2. While Toto nozzles exclusively use EWATER+, which is electrolyzed water used in many applications as a cleaning agent, they do not see stainless steel as a necessary upgrade to their nozzles.
In Summary
While minute, there are benefits to stainless steel over plastic or aluminum bidet nozzles. As the stainless steel nozzle is a recent development in the bidet world, plastic nozzles and Toto's belief in them have been commonplace for the majority of the electric bidet's existence. If your personal preference leads you towards stainless steel, you now know that in either case the overall experience of a bidet will not be compromised by the material that your nozzle is made of, and that there are many options across brands to suit your needs.