As of 2016, all dairy farmers are required to properly treat their milk house wastewater prior to disposal. Dairy farmers are interested in a low cost and effective treatment technology to apply. The objective of this presentation is to outline the design, construction and analysis of a Horizontal Subsurface Flow Constructed Wetland (HSSFCW) technology coupled with the use of a passive phosphorus (P) filter to treat milking centre wash waters and/or barnyard runoff in three different sites in Canada. A HSSFCW technology can enable farms to divert wash waters from liquid manure storages, with potential wastewater re-use. The passive P filter, can help remove the high levels of phosphate in the wash waters.