Location of the H₂O emission for a typical disc model (M_∗ = 0.8   M_⊙, L_∗ = 0.7   L_⊙, T_eff = 4400   K, UV excess f_UV = 0.01, X-ray luminosity L_X = 10³⁰ erg s^-1, R_in = 0.1 AU, R_out = 300 AU, M_disc = 0.01   M_⊙, dust/gas = 0.01, ϵ =  −1, scale height H₀ = 1 AU at r₀ = 10 AU, flaring β = 1.1, astronomical silicate with uniform dust size distribution a_min = 0.05 μm, a_max = 1 mm, and index = 3.5). The 15.738 μm line is used as a typical H₂O line detected by Spitzer. We have marked the radii where the cumulative line flux reaches 15% and 85% with vertical lines, for the four selected H₂O lines. In addition, the horizontal lines mark the heights above the midplane where 15% and 85% of the line flux, from every vertical column, originate in. The encircled regions are hence responsible for 70% × 70% = 49% of the total line flux (for a pole-on disc).