A 304 stainless steel drainage grate and a 316 stainless steel drainage grate differ primarily in their composition and corrosion resistance. 304 stainless steel is a versatile and commonly used grade known for its excellent corrosion resistance in various environments, making it suitable for many applications.

316 stainless steel contains higher levels of chromium and additional elements like molybdenum, which enhance its resistance to corrosion, particularly in harsher conditions such as marine environments or exposure to chloride-containing solutions.

Within a kilometre of breaking surf, 316 stainless is recommended to be utilised. Additional care will still need to be undertaken to prevent tea staining. See more about the maintenance of stainless steel here.