Backflow is the reversal of flow of water or other substances through a cross-connection into the public water system or consumer's potable water system. There are 2 types of backflow - Backpressure backflow and back-siphonage.
Federal and State regulations require public potable water supplies to adopt rules to prevent contamination in their water systems. To comply with these mandates, the San Marcos City Council has adopted an ordinance, the Cross Connection Control and Backflow Prevention Program, to protect the City's potable water supply from contaminants back-flowing from a customer's water system. Article 9, Chapter 86 of the City Code establishing this program was approved August 13, 2001 (See the City's press release regarding backflow prevention).
Please note that any new backflow installations or replacements are required to pull a permit through the Permit Center of the City's Planning and Development Services Department. Please see their webpage for more information on permitting.