Previous studies have shown that long-term irrigation with wastewater can lead to the development of soil water repellency. Little is known about the longevity of this effect. Here we address this research gap by examining the effect of long-term (~ 20 years) use of low-quality wastewater for disposal purposes, followed by 6 years of ‘recovery’ with no irrigation, on the wettability of calcareous sandy soil (Xerofluvent) under a Populus alba tree stand used as a “green filter” in SE Spain. Water repellency (WR) and soil organic matter content (SOM) were determined for 120 air-dry samples from the plot and 80 control samples from adjacent and otherwise similar non-irrigated areas. To account for plot micro-topography 40 samples each were taken from ridges (R; 0–5 cm depth), furrows (F; 0–5 cm), and furrows at depth (FD; 5–10 cm). The controls included 40 samples each (0–5 cm depth) from unvegetated and unploughed soil, and from soil under the P. alba plantation.