This study examines innovative irrigation optimization strategies for arid regions by integrating treated wastewater and novel subsurface irrigation techniques. Conducted in Ouargla, Algeria, over a 120-day growing season from December 2023 to March 2024, the research employed onion cultivation as a representative crop (N=240 plants) to evaluate a hybrid irrigation system combining precision drip irrigation with sand-filled plastic bottles for enhanced water efficiency and natural filtration using a randomized complete block design (RCBD) with four replicates. The experimental design incorporated perforated bottles with 2 mm diameter holes, geotextile fabric wrapping, and local dune sand filling to create an effective subsurface water delivery and treatment system. Irrigation scheduling was optimized by comparing theoretical water requirements calculated using CROPWAT software with experimental soil moisture measurements. Results demonstrated that the sand-bottle system achieved water use efficiency (1.42±0.06 kg/m³) statistically equivalent to freshwater irrigation (1.51±0.08 kg/m³) using TOST equivalence testing with ±10% margin showing strong correlation with theoretical predictions while consuming 23% less water than conventional drip irrigation with treated wastewater (240±18mm vs 310±15mm). The sand filtration component effectively reduced biological oxygen demand by 25.3 on average, chemical oxygen demand by 7.76-29.3%, and suspended solids by 57.71-66.44%. However, electrical conductivity increased marginally (5-9.5%) due to salt leaching from sand particles. The system demonstrates sustainable irrigation potential for water-scarce environments, though monthly sand replacement is required to maintain optimal filtration performance.