The grade is important, but it is not the whole specification
304 and 316 stainless steel are often presented as a simple good-versus-better choice for coastal bathrooms. In practice, the correct selection depends on where the product will sit, how much salt reaches it, whether the surface stays wet, the finish, fabrication quality and the manufacturer’s approval for that use.
316 generally offers greater resistance to chloride-rich exposure than 304, but it is not a universal guarantee against staining or corrosion. A badly contaminated, rough or poorly maintained surface can still perform badly.
Location changes the decision
A fitting in a protected internal bathroom, one beneath a salt-laden open window and one in an exterior shower do not experience the same environment. Distance from the sea is useful context, but wind, shielding, height, surf and rain washing also matter.
The material should be chosen against the exposure category rather than a postcode alone.
Ask for the evidence
Confirm the actual base metal, surface finish, cleaning instructions, warranty exclusions and replacement route. If the product is assembled from multiple metals, the hidden fasteners and contact points also deserve attention.
304 versus 316 is a useful question. It is not the complete coastal specification.
Continue with why stainless steel can still rust in Umhlanga, or see coastal material planning for Umhlanga and the North Coast.