The invention relates to a geotextile (12) that is treated with: a metal such as copper to prevent plant roots or microorganisms growing on and through the geotextile (12). The geotextile (12) is used in conjunction with a subsurface fluid supply system (10), where the treated geotextile (12) prevents the ingress of roots into drippers (13) that are disposed on conduit (11) of the fluid supply system (10).