Water Gravity Fed for 167 miles?

Kristyn Hanson

Water gravity fed for 167 miles?

Not only does the city of San Francisco get some of the most pristine water delivered to they also get it delivered completely gravity fed with no pumping needed along its journey. This fact was completely mind blowing for me. Their water comes from a National Park, it doesn’t have to be treated, and doesn’t require outside power to transport it. I always knew about the Hetch Hetchy Project but I had no idea about these facts.


The water in this system is some of the cleanest water in the country and is one of the six water systems in the US that does not require filtration. The Hetch Hetchy reservoir is protected from human contact. There is no swimming, no boating, and to the best efforts no animal contact. The only boat seen on this beautiful water is a maintenance boat. There is little sediment in the water since the geology in this region mostly consists of granite. The water seen in this reservoir was clear blue and absolutely beautiful, you could see why filtration wouldn’t be necessary. The water is exposed to UV rays and is lightly chlorinated and then it’s ready to be supplied to the millions of people in the San Francisco region.


After the water leaves Hetch Hetchy Reservoir it starts it journey through the Canyon Power Tunnel and then the Mountain Tunnel. From here it takes a stop at the Moccasin Powerhouse and Don Pedro Reservoir, which we got the opportunity to tour. The water here is also untouched and sees its last bit of sunlight. After this the water starts its journey down the Hetch Hetch y Aqueduct to San Francisco. The water is divided into four different pipelines. Two go to the San Francisco bay and the other two go to Pulgas Water Temple. The water is completely gravity fed and doesn’t require any pumping or added energy.