What is the minimum vertical separation required when installing collection systems lines in relation to water lines?

The minimum vertical separation required between collection system lines and water lines is commonly established to prevent the contamination of the potable water supply. A separation of 18 inches is specified in various standards and guidelines, including those from the Environmental Protection Agency (EPA) and state regulations, to ensure that any potential leakage from wastewater collection systems does not contaminate drinking water sources.

The 18-inch standard allows enough vertical clearance to minimize the risk of cross-contamination that could occur due to structural failure, pressure changes, or other factors affecting either system. This separation is crucial in maintaining public health and safety, as it helps ensure that wastewater does not interfere with the integrity of water supply systems.

While other separation distances exist, they may pertain to different conditions or practices, but the 18-inch standard is a widely accepted minimum in many jurisdictions, making it the correct choice in this context.