Here we just illustrate that even under typically experimental conditions, the small amount of the trace organic contaminants dissolved in the so-called "pure" solvent is sufficient to supply the amphiphile molecules for stabilizing a large number of bulk nanobubbles. Many experiments reported the observation of stable nanobubbles in the typically pure water (<50ppb) system, and the concentration of bulk nanobubbles is mostly around 𝑐 ~10 /𝑚𝐿, with a typical bubble size around 100nm.