Overstanding SF Water

HetchHetchyReservoirSmallThis following I wrote in response to a chain of comments about the quality of SF Water on the Permaculture SF email list.

The original question asked, “anyone have any idea on the quality of water in SF? Secondly, can anyone recommend a good affordable filter that mounts on your sink?”

One Comment that followed added, “The water in San Francisco is some of the best and comes to us from the Hetch Hetchy Reservoir in Yosemite. It gets here by way of the Hetch Hetchy aqueduct.  I have a poster of the water system in my bathroom!  So don’t fret and drink up.  I grew up in Healdsburg and that water scares me.  I <3 SF H2O.”

Me? I love water, and I am truly gratefuil to have running water in my home.


I Would like to add some facts for us to think about. While the Hetch Hetchy reservoir in Yosemtie sounds awful nice, picturesque and pristine, that water travels a long way to get here in some pretty old pipes through some questionable agricultural land.

Our water is in fact treated with Chloramines and not simply chlorine. chloramines (mono, di, and tri-chloramine) are chlorine bonded with ammonia. Normally, chlorine gasses out of water relatively easy within 24 and even faster in the presence of solar radiation. Chloramine on the other hand does not, and in fact cac stay in water for years without leaving. It iwll degrade slowly from mono-chloramine to di-chloramine and then tri-chloramine which is the most toxic.

Chlorine is very toxic and damages the gills of fish so they cannot breath and can kill them. Aquarium owners must now buy a special treatment for their tank water when they clean their tanks or kill the fish. Same for pond owners. It also damages the reproduction cycle of amphibians. When our city water leaks into waterways, it tends to kill lots of the life there.

Chloramine has the same effect as chlorine, except it stay for much longer in the water.

Additionally, chlorine kills microbial life, in fact that is why it is used in our water supply. You cannot brew compost tea with SF city water.

I wont comment on this and you can ask yourself what it does to soil when you water the garden, or what it does to your intestinal flora when you drink it. I drink it, I feel ok, but I just don’t know. Some people have reported severe skin allergies.

Learn more about chloramines from a local non-profit:

Also consider how far the water travels before it hits your faucet. It crosses the Central Valley and rests for a bit in Crystal Springs before it is pumped over the hill and sits in a reservoir in SF. Most people in SF drink water from University Mound Reservoir which is a huge cement underground structure built in the 1920’s and sits just a block downhill from my house, right next to an athletic field. I am pretty sure the gardeners dont bother to use herbicide on the field.


About filtration. I HIGHLY recommend it. Advertising campaign statements such as, “Hetch Hetchy water is some of the best in the country” are pseudo-information. Relative to what? “Some” of the best? I know people suffer horribly from their local water all over the country, is better than that good enough? All questions to ask yourself, I am not here to tell you what I think is right or wrong.

KDF will filter chlorine, activated carbon some of the other stuff. How effective they are is determined by the size of the filter, the amount of throughput, and the residence time of the water against the filter medium. For drinking water from a faucet, i recommend one of these under-sink units with KDF such as the one linked in this chain or I will link another I have used below this paragraph. A good strategy would be to SLOWLY fill a pitcher or container from your filtered faucet and keep that for drinking water. Also remember that when you cook things such as pasta, rice, beans you should use filtered water, fill your pots slowly.]

WATER FILTERS (note he sells a whole house filter, i have installed one of these and it works very well):

Please take into consideration embodied energy when thinking about a filter solution. There are also slow sand filters, a low tech solution and a good strategy used in emergency situations:
Google Search for “Slow Sand Filter”

For the garden, it is very helpful to know that biology will do the work for us. Ammonia is in fact a form of nitrogen and life will use it up if it is available. If you have a small pond, you can add small amount of city water to the pond and the life that is present will consume the ammonia, thereby breaking the bond with the chlorine and the chlorine will then be able to gas off freely. Be careful not to add too much at once and you should be fine. I am waiting to see some clever garden hydration strategies that involve using a pond that overflows and spreads the water on contour to beds. You can use rainwater for compost tea, I have not tried using pond water for compost tea but that will be one of my next experiments.

The point of this is not to advocate the consumption of bottled water. I just want to add some easy to find facts to the discussion so that we may OVERSTAND the SF water issue. This article is also not meant to be an exhaustive exploration of all the aspects of the conversation. Please leave your comments and let’s have a healthy discussion about it.

1 Response

  1. January 21, 2017

    Great News

    This story was very interesting. Thank you.