Random Videos on Instagram: "That black water from a fire sprinkler isn’t just old and dirty; it’s the result of a fascinating chemical and biological process that happens inside the pipes over many years. Most sprinkler systems use steel pipes that are constantly filled with pressurized, stagnant water. Over time, this water causes the pipes to slowly corrode. The dark black color is primarily due to fine particles of iron sulfide, a compound that forms as a result of this long-term corrosion.