How much water is too much water? | A new shade of green | Sherry Listgarten

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A new shade of green

By Sherry Listgarten

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About this blog: Climate change, despite its disproportionate impact on the planet, remains an abstract concept for many of us. This must change. I hope readers of this blog will develop a better understanding of how our climate is changing and… (More)

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Uploaded: June 19, 2022

We’re in our third drought year in California and it’s not pretty. SoCal residents are under unusually severe restrictions. Our area has looser boundaries, but this may get tighter as the summer progresses. Many of us try to use less water, but it gets harder over time and it would be nice to know when you’ve done enough. Hence the title of this blog post: How much water is too much water?

Unfortunately, I don’t have many more answers on this subject than you do. Probably, if you have a lush green lawn and your irrigation is creating puddles on the street, you are using too much.

And probably if your garden looks like this, or you don’t have one, you’re doing pretty well.

But there are a lot of works in between. All of the yards pictured below look great and appear to have fairly drought tolerant plantings. Residents may be wondering if they are saving enough.

How do we know we’ve done enough? I have no idea. But I thought I’d share how much water my house uses and maybe you’ll share yours and we’ll have a collective idea of ​​where we stand.

My house uses a boatload of water, despite our efforts over the past three years to use less. Here is a chart showing our monthly water consumption.


Monthly water consumption at my home from January 2017 to May 2022

You can see that our water usage is almost entirely for irrigation, which is withheld during the winter months. (1) In 2019 our gardener changed all irrigation to once a week. You can see that we used less in the hot summer months, but we used more in the other months because there was little rain. (The peaks in the graph are shorter but wider.) Look at how much water we used in January and February 2021 compared to previous years. It’s ironic that when there’s a drought, you end up needing to use more water.

Last summer, our gardener reduced watering even further, watering several areas only once every ten days (2) and further reducing watering times. I knew we would lose the most thirsty plants but that was okay. It was kind of survival of the fittest competition. The backyard lawn started to look worse and worse and in September we covered it with mulch.


We mulched the lawn last fall.

I don’t know what our water usage will look like this summer, but I think we made a decent dent from 2019 and even 2020-21.

But is it enough? We still use a lot of water. If we use 10 CCF (3) in a summer month, which is a lot of savings, it’s still about 250 gallons per day. With only two people in the house, that’s 125 gallons per person per day. The map in this article shows that the per capita water consumption in 2020 in East Palo Alto was 40 gallons per person per day, 64 in Mountain View, 71 in Menlo Park, and 101 in Pleasanton. Oh, hey, it’s 125 in Los Altos. I’m not alone! (To be fair, though, the average month with us is probably under 10 CCF.)

Last summer, I measured our water intake every day for a few months.

Irrigation days dominate, using over 750 gallons of water (100 cubic feet). On other days we use between 4 and 10 cubic feet, or 30 to 75 gallons. Even that seems like a lot to me. When we didn’t have showers, laundry, or dishwashers, we still used 30 gallons. On what? But the meter shows no leaks and given the extent of our irrigation usage, I didn’t bother to investigate.

Could we use less if requested, without killing even more plants? I am not sure. The land is large – 9200 square feet – and the house and driveway take up only 2500 square feet, leaving plenty of greenery that needs watering. There’s a large pepper tree out front, an even bigger elm tree in the back, and all sorts of hedges, small trees and shrubs galore. They are established plants, not very water-intensive, but they still need water. Frontal irrigation works every ten days, one zone for 15 minutes, another for 10 and one drip zone for 45. Rear irrigation works every week, with five zones at 15 minutes and one drip at 30. That’s about 2.5 hours a week, and will likely be more as the days get warmer. (4)


Some of the plants I water.

Also, at some point I want to plant the recently mulched area in my yard, which means even more water usage, especially when the plants are young. I will try to select drought tolerant natives, but still.

Where is all this going? I don’t think Palo Alto will send the Plant Police, but I wonder how it will go. If the drought persists, how should we develop our sites? I do not know.

Does anyone else want to share how much water you use, where you saved water, where you think most of your water now goes, and if there is anywhere you can not imagine reducing?

Notes and References
1. There is still irrigation in the winter, under the extended roofline.

2. Before that, I didn’t even know you could water every ten days. The corresponding setting is called “Skip Days” on my Rainbird irrigation box.

3. 1 CCF = 100 cubic feet = 748 gallons.

4. I don’t know what types of spray heads the irrigation uses or more generally how much water each zone uses per minute.

Current climate data (May 2022)
Global impacts, US impacts, CO2 metric, climate dashboard

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