The San Francisco Public Utilities Commission owns and operates more than 1,200 miles of water pipelines in San Francisco. These water pipelines, also called water mains, deliver high quality drinking water to your tap. Approximately 20% of San Francisco’s water mains are about 100 years old and need to be replaced. We replace or rehabilitate aging and vulnerable water mains each year using two construction methods: open-cut and trenchless. Open-cut construction is typically used for water main replacement, while trenchless methods are used to rehabilitate existing water mains with minimal