Aspect ratio H/r for discs with different water-to-silicate ratios. The top plot shows H/r for a dust metallicity of Z_dust = 0.5%, while the bottom plot has Z_dust = 0.1%. A larger fraction of water causes a larger bump in the H/r profile at the water ice line, as expected from the opacity transition (see Fig. 1). At lower dust metallicities the bump at the water ice line is less pronounced compared to higher dust metallicities and resides close to or even inside of 1 AU at the late stages of the disc evolution. For all water-to-silicate ratios, lower accretion rates Ṁ result in smaller H/r, because the disc is less massive and therefore produces less viscous heating.