Unless you stick your head inside your washing machine, you might not even know what your machine's wash drum or tub is made of. The machine's tub material is a significant factor in the lifespan of your washer, as well as in its ability to treat your clothes well, and in just about every respect except for cost, stainless steel has an advantage over other tub materials.
The wash tubs in most modern washing machines are made from one of three materials. Steel tubs with a porcelain enamel finish, much like a porcelain bathtub, are the most traditional option, and they're most common in low-end and mid-range washer models. Tubs made from heavy-duty polymer plastic are a durable, inexpensive alternative. More expensive washing machine models often feature stainless steel tubs.
In terms of longevity, porcelain tubs are the most problematic. Over time, the porcelain enamel may chip or wear away, exposing the steel underneath; the exposed steel will rust, which can weaken the tub and stain clothing. Both plastic and stainless steel tubs are durable and will likely last as long as the rest of the washing machine. Stainless steel tubs, though, are stronger than plastic tubs and can hold up to higher spin speeds; because higher spin speeds remove more water from clothes and make laundry easier to dry, this is an advantage that can make stainless-tub-equipped machines more energy-efficient overall.
Resistance to Stains
Both the plastic and porcelain used in washing machine tubs are porous, and the tub surfaces can absorb stains and odors; in time, the interior of porcelain and plastic tubs may become discolored and smelly. Stainless steel, in comparison, is much less porous and much less likely to accumulate stains and odors over the life of the machine.
As a plastic tub wears with use, it develops a rough surface that can snag and pull on laundry during the wash cycles, causing significant wear on your clothes. A stainless steel tub doesn't get rough and may in fact get smoother as it wears, so it's considerably less likely to damage clothing.