I studied a similar problem during my PhD. You can estimate the range using equations I developed in my dissertation, though they can get messy. Unfortunately, the dissertation is presently embargoed due to some chapters being published in a journal, but the trajectory chapter is not bound by such rules and I have uploaded it here.
The theory in my dissertation considers the breakup of the jet and the droplet size. It does not consider evaporation, which I don't believe to be a significant factor in most instances. The theory requires the firing angle to be less than about 40 degrees or so, which is fine in most instances.
The equation for range (equation 7.75, p. 193) in my dissertation follows:
$$R = d_0 \left[\frac{\langle x \rangle_\text{b}}{d_0} \cos \theta_0 - \frac{a}{b C_\text{d}^*} - \frac{1}{C_\text{d}^*} \mathrm{W}_{-1}\left(-\frac{\exp(-a/b)}{b}\right)\right],$$
where $R$ is the range, $d_0$ is the nozzle diameter, $\langle x \rangle_\text{b}$ is the jet breakup length, and $\mathrm{W}_{-1}$ is the -1 branch of the Lambert W function (available in Python, Matlab, etc., though not Excel). The remaining terms are more complicated:
$$C_\text{d}^* = \frac{3}{2} \frac{C_\text{d}}{\rho_\text{l} / \rho_\text{g}} \frac{(1 - \alpha)^2}{D_\text{max} / d_0},$$
$$a = 1 + {(C_\text{d}^* \cos \theta_0)}^2 \left[\left(\frac{\langle x \rangle_\text{b}}{d_0} \sin \theta_0 + \frac{h_0}{d_0}\right) \mathrm{Fr}_0 - \frac{1}{2} {\left(\frac{\langle x \rangle_\text{b}}{d_0}\right)}^2\right],$$
$$b = 1 + C_\text{d}^* \cos \theta_0 \left(\mathrm{Fr}_0 \sin \theta_0 - \frac{\langle x \rangle_\text{b}}{d_0}\right),$$
where $\mathrm{Fr}_0 = \overline{U}_0 / (g d_0)$ is the Froude number, $\overline{U}_0$ is the jet velocity at the nozzle exit, $h_0$ is the firing height and $\theta_0$ is the firing angle.
If you want to avoid the Lambert W function, it's not hard to implement a numerical simulation along the lines of the model described in my dissertation.
For the particular case described, I'd expect the breakup length to be very short, and it might be reasonably approximated as zero. You'll need values of $D_\text{max}/d_0$ and $\alpha$. These numbers will change from case to case. I used $D_\text{max}/d_0 = 0.7$ (p. 198 says 0.8, which is in error though not by much) and $\alpha = 0.05$ for fire hose jets. Those numbers are not likely useful for the particular case described by DrM. I'd expect more air entrainment (higher $\alpha$) and smaller droplet sizes in that case.
