Sunday, November 25, 2012

Sustainable Living – One Step At A Time: Water Conservation

I want to apologize to my readers for not having posted anything in a long time. Ironically, working within the sustainable chemicals field sometimes makes posting about new topics even harder. I have become even more busy over the last couple of months. But my determination to keep this page going has strengthened even more since I have become a father. And the reason for this is simply that preserving the environment or at least helping to setup a frame-work that makes sustainable living possible in the future has become even more important to me now that my son was born.



So today, instead of talking about grand ideas, I will just be writing about efforts in my home that I have undertaken to reduce my families impact on the environment. My topic today: Water usage and water conservation. People often talk about a carbon footprint, but the water footprint is of at least equal importance. That's because although ~70% of the earth is covered in water, only 3% of that water is actually drinkable. Pollution and waste endanger this scarce resource - potable water. In dry and populated regions such as Southern California, water scarcity should be an even more important issue than it appears looking at the current mainstream media landscape.

Be it as it may, posts titled "Sustainable Living - One Step At A Time" are meant to give concrete steps of things individuals can do to make the world a better place. So let me share with you what I have done. All this was done over the last 11 months as my goal for this year was to make the house 33% more water efficient.

Let's start with taking inventory of what we had before the upgrades:
  • 3 bathroom faucets rated at 1.5 gpm
  • 2 showerheads rated at 2.5 gpm
  • 1 kitchen sink faucet rated at 2.5 gpm
  • 2 toilets rated at 1.6 gpm
  • 1 dish washer that doesn't get used.
  • 1 HE front-loading washing machine

The following water usage patterns arise assuming that:
  • 3 bathroom faucets each get used for 5 minutes per day (22.5 gallons)
  • 2 showerheads each get used 20 minutes per day (100 gallons)
  • 1 kitchen sink faucet gets used 20 minutes per day (50 gallons)
  • 2 toilets each get used 6 times per day (19.2 gallons)
  • Washing machine gets used 1 per day (14 gallons)
The total estimated water consumption per day then is 205.7 gallons of ~ 781.7 L. Scaled out to a month this equals to about 6171 gallons and about  74052 gallons per year. Just as a comparison, the average backyard pool holds about 15000 gallons. So the yearly water consumption before upgrades equals about 4.9 backyard swimming pools.

Over the past 11 months, I have made the following upgrades:

Replaced all 3 bathroom aerators with 1.0 gpm aerators
Replaced two showerheads with a 1.0 gpm and 1.25 gpm showerheads
Replaced the kitchen sink faucet with a 1.5 gpm rated faucet.
Replaced broken toilets with 1.0 and 0.8 gallons per flush HE or UHE toilets.
I have also convinced my mother-in-law to use the dishwasher once at the end of the day instead of washing everything after lunch and dinner.

What savings am I getting out of all these changes?

The following water usage patterns arise assuming that:
  • 3 bathroom faucets each get used for 5 minutes per day (15 gallons)
  • 2 showerheads each get used 20 minutes per day (45 gallons)
  • 1 kitchen sink faucet gets used 10 minutes per day (15 gallons)
  • 1 dish washer gets used once a day (6 gallons)
  • 2 toilets each get used 6 times per day (10.8 gallons)
  • Washing machine gets used 1 per day (14 gallons)
After the upgrades the estimated water usage per day is 105.8 gallons or ~402 L. This equals to 3174 gallons per month or 38088 gallons per year. So I have achieved a roughly 51.2% reduction in water consumption. In easy to see terms, I have cut the water consumption of my household down from 4 swimming pools down to 2.5 swimming pools.

How much of an improvement do these measurements make? According to an article by the Sierra club, the daily average per capita (person) public water consumption for San Francisco was 108 gallons in 2008. Compared to that the measures introduced here lead to a per capita use of just 24.75  gallons/day. I am surprised that the  numbers are so low given that I started out low already at 47.5 gallons/day. Perhaps this is due to the fact that I have not counted outdoor water usage.

There is only very little now that can be done in a cost-effective way. Replacing an already working toilet for $300-$400 (including labor) just to save another 0.2 gallons per flush is not feasible. The only other possibility to save more water is to replace the other showerhead down to a 1.0 gpm showerhead which would save another 5 gallons and through behavioral changes. Looking at what I sought to achieve though, I think for indoor water usage, I have achieved my goal. I emphasize indoor water usage because landscape irrigation in California is a much more significant source of water usage - especially in the dry summer months. This will be the next project I will work on over the coming year.


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