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 aging and vulnerable water mains each year. The process of replacing aging water mains involves many steps. Construction will not happen all at once. Crews will need to return to the same block several times to work, often with months between visits. Water main