Chlorpyrifos is an organophosphorus pesticide widely used in Colombia for agricultural and domestic pest control. It is also commonly found in water sources in rural areas. Constructed wetlands are being used as viable alternatives for the treatment of domestic wastewater with large organic loads. For this research, three pilot-scale subsurface horizontal flow constructed wetlands and three horizontal surface flow wetlands were used for the treatment of synthetic wastewater with different concentrations of chlorpyrifos (.μgL⁻¹, 478μgL⁻¹, 589μgL⁻¹ and 788μgL⁻¹), 1mgL⁻¹ of dissolved organic carbon and nutrients. The wetlands were constructed in equal dimensions and in the same size range as the gravel bed (3.18–6.35mm) and planted with Phragmites australis. The efficiencies of the removal of the pesticide and dissolved organic carbon were then determined. Additionally, other physicochemical parameters, as well as 3,5,6-trichloro-2-pyridinol, the main breakdown product of chlorpyrifos, were measured. The average removals of this agrochemical and dissolved organic carbon in the subsurface horizontal flow constructed wetlands were 93% and 92%, respectively, and in the horizontal surface flow wetlands, the average removal was 95% for both compounds. The removal is the result of the joint action of microorganisms and the adsorption and absorption of roots and rhizomes of plants found in wetlands. Both types of wetlands are very efficient at treating the domestic wastewater contaminated with pesticides and dissolved organic carbon, although the results were slightly better in the surface flow wetlands. SSFCW and SFCW achieved high removals of chlorpyrifos pesticide and DOC. Average removal of chlorpyrifos in the SSFCW was 94% and in the SFCW was 95%. Average removal of DOC in the SSFCW was 92% and in the SFCW was 95%. Surface and subsurface wetlands with Phragmites are effective for removal of pollutants.