If you are assessing a property for installation of a septic system at a site with a production well which is operated under the authority of the Health Ministry, the well must be 300 m from the septic system so that you do not trigger a designation of Groundwater At Risk of Containing Pathogens (GARP). See page 59 in the linked document Stage 1: Hazard Screening and Assessment B4: Located within 300 m of a source of probable enteric viral contamination without a barrier to viral transport.