In this work, we irrigated myrtle plants with reclaimed waters (RWs) for 90 days with drainage. The treatments consisted of a control (0.8 dS m−1) and two RWs: RW1 (2.0 dS m−1) and RW2 (5.0 dS m−1). In general, nutrients were accumulated in a greater proportion in shoots than in roots and increased in the RW treatments, with the exception of potassium and phosphorus. This behaviour produced a progressive decrease in the root water potential, which hindered the mobility of water to the leaves. This in turn caused a drop in leaf water potential and gas exchange parameters, especially in the RW2 treatment. The intrinsic water-use efficiency (WUEi, Pn/gs) did not show differences in any treatment. The RW2 treatment provoked a loss of biomass in the leaves but not in the stems and roots, resulting in more compact plants. Considering these results together, it is feasible to use RWs for plant irrigation, despite their high electrical conductivity. RWs are thus a viable alternative to scarce conventional water resources in a future scenario of climate change.