According to ANSI Z 358.1, there are two kinds of eyewash stations that are acceptable. They can be either plumbed or self contained (also called portable or gravity fed). Plumbed eyewash stations are permanently fixed to a source of clean, unlimited water. Self contained eyewash stations are portable, stand alone, units that contain enough solution to flush the eyes for at least 15 minutes. Squeeze bottle flushing units are not an approved eye wash option according to ANSI.