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Water Efficiency Series: Part 3- Water Scarcity, Awareness and Rainwater Harvesting

May 9th, 2011 by

When looking at a map it appears that we have more than enough water to sustain all of the earth’s inhabitants with plenty of clean water.  However, less than 1% of this water can meet human’s freshwater needs. (Source: Sherwood Institute Blog “All the Water in the World”, Aug. 25 2010).  At present there are water wars in countries around the globe because of the scarcity of the valuable resource. Meanwhile, in many countries (such as the U.S.) we are over-using water without even thinking about it.

My best friend lives in St. Thomas. When I visited her last year, I was amazed that ALL of the water she used was rainwater from a rooftop catchment system.  I was there for 10 days and in that time quickly adapted to “West Indian Showers” (turning on the water only for a few seconds at and the beginning and end of your showering process), using the absolute minimum amount of water for dishwashing, and learned the phrase “in this land of fun and sun, we don’t flush for number one!”

Picture from sign in bathroom of Soggy Dollar in Jost Van Dyke, BVI Source:

Although the island life takes a little getting used to, when I returned home I was SO conscious of just how much we, as a society, waste water.  My roommate would defrost chicken by running cold water over it- for hours! Despite my complaints and explanations of why it was wasteful, she couldn’t understand that water is a precious resource.

Compared with other developed countries, the United States has some of the lowest water/wastewater costs as a percentage of household income.  I know that when I became responsible for paying gas and electricity bills, our thermostat turned down and I became much more conscious of conserving energy.  As a renter, I have still never had a water bill in my name, as is the same for most young people.  Water seems free, and even for my landlord who is footing the bill; it is a very low cost utility.

At present, the cost of water does not reflect the value of the resource.  Water infrastructure is aging and revenue generated from the sale of water is needed to improve water services.  Increasing the price of water will not only generate revenue to improve the infrastructure but should also help to make the public understand that water is a valuable and precious resource.

In the United States, we are lucky to have infrastructure for delivering water conveniently and cheaply to our faucets. However, it takes a huge amount of energy to transport and treat water.  Rainwater is an under-utilized resource that can be used as potable water without extensive pumping and treatment.

In many areas of the world, rainwater is used for everything: showering, drinking, dishwashing, irrigation and toilet flushing.  However, in developed countries, which do have advanced water infrastructure, rainwater is generally used only for non-potable uses such as irrigation, toilet flushing, laundering, emergency water supplies, fire prevention use and process water uses.

Rainwater harvesting is a very scalable technology that can be as simple as catching rainwater from the roof and delivering it to storage tanks for irrigation or can be as complex as a large cistern with treatment processes for indoor use.  It is important to match the rainwater use to the level of treatment provided.  Water used for irrigation does not need to be treated to potable water standards, as that would be a waste of time, energy and money.  However, if the water will be used indoors, it is important to insure that it is adequately treated to mitigate health concerns.

Simple rainwater catchment system Source:

Complex rainwater harvesting system with ozone and UV treatment Source:

There are so many benefits of rainwater harvesting! These include (but are not limited to): minimizing stress on municipal systems (supports supply and reduces infrastructure maintenance costs); reducing energy required for treatment and pumping of centralized systems (thereby reducing greenhouse gas emissions); providing independent water security especially in times of natural disaster; often providing cost savings over time; decreasing municipal stormwater intake (thus reducing flooding, lessening quantity of stormwater needing treatment, and minimizing sewer overflow); and offering community benefits such as open green areas, public water awareness and self sufficiency.

Although using rainwater can be very beneficial, it is important that the catchment systems are designed well and with caution.  Most concerns are related to health concerns from biological or chemical contamination. However, in good designs most of these worries are minimized.  It is important that municipalities recognize the benefits of rainwater harvesting and create guidance to encourage safe catchment system design. Equally important is for citizens to use these regulations when building a system.   Lastly, it is important that systems are inspected regularly to insure against contamination and to ensure that the water stays at a healthy pH level.

In conclusion, it is important to grow awareness in many developed countries about the scarcity of water.  One way of doing this is by raising water prices to full-cost pricing.  Once people become more conscious that we need to look at other water sources, hopefully rainwater harvesting will become more popular.  Rainwater catchment systems are very scalable and have many benefits, but most be designed cautiously to ensure the rainwater remains safe.  Hopefully, systems will become more prevalent to reduce the impact on current infrastructure and to ensure security to our water systems.

Sustainable Solutions for Hot Water Production and Water Conservation

February 22nd, 2011 by

As I have previously mentioned, I live in Lake Tahoe, CA.  Although it has been abnormally warm this year (60 degree spring-skiing days in January!), the water in our house runs SO cold for SO long!  Since we keep the house at a pretty chilly temperature, this icy water makes for a very unpleasant hand washing experience.

Despite doing things like brushing my teeth and letting the water drip for the cat (my crazy Bengal refuses to drink anything but water from my own drinking glass or a running faucet!)  BEFORE washing my hands, the water still needs to run for far too long to get warm. Or I have to suffer and have freezing cold hands!  I have also heard many people complain about how cold the water is in the public bathrooms at the ski resort.

People in cold ski towns don’t like cold water.  So, I decided to learn more about sustainable ways to heat water and reduce the use of un-used, cold water.

Sasha drinking water from the faucet

A few facts about unused water waste:

-Running the water for a few minutes, even with low-flow fixtures, wastes approximately 3-5 gallons of water.  For a family of four, that is about 15,000 gallons of water a year.

-If someone drinks the recommended 8 cups of water a day, that is only 185 gallons of water needed per year.  Meaning, just by running water, waiting for hot water, you could be wasting about 20 times the amount of water you drink per year.

-Running hot water is a huge energy drain! Running your faucet with hot water for 5 minutes is equal to the energy usage of a 60-watt light bulb for 14 hours!

The good news is, there are many ways to maximize water and energy efficiency for hot water.  These include using low-flow water fixtures, insulating hot water tanks and piping, planning hot-water tank placement to minimize piping, using EnergyStar and WaterSense rated appliances, and being conscious of water usage when taking showers, brushing teeth, washing dishes and laundry, etc.

In addition to all of these improvements, there are a lot of choices to make when deciding what the best type of hot water heater to use (tankless, on-demand, re-circulating systems, solar-hot water… the list goes on).  For this blog I am going to focus on residential hot water, highlighting one system for energy efficiency and another system for water efficiency.

One of the most sustainable methods for heating water is solar thermal (heating water using solar radiation). This is discussed in Sustainable Infrastructure: a Guide to Green Engineering by S. Bry Sarté. This heated water can be used for residential hot water, hydronic radiant floor-heating systems, heating swimming pools, and even commercial electricity generation.  A typical solar hot water system can provide enough hot water for the average home.

Solar thermal collectors are generally black coils filled with water, which are installed on the roof.  The water heats up in the sun and then is stored in a tank until needed.  Systems are almost always constructed with an auxiliary water heating system that is activated if the water drops below a set temperature so that hot water is always available.  Solar thermal hot water generation is a relatively cheap system, much less expensive then solar photovoltaic panels used for residential electricity generation, so they can be a nice place to start when greening your home.

Solar Thermal Hot Water System Diagram, image from:

Solar thermal systems can be passive or active.  Passive systems use convection to naturally move the warmer liquid (water or a antifreeze heat transfer fluid) to the storage tank and cold water to the collectors for heating.  These systems are simpler and less costly than active systems but can only be used in moderate, sunny climates.

Active systems use pumps to move water from the collectors to storage tanks.  This allows the tank to be situated under the collectors, which can increase efficiency since it can be stored indoors in a more insolated space.  A controller is also used to ensure that water is only being pumped when the water in the collector is warmer than in the tank.  In addition to increased efficiency, active systems have less risk of overheating and freezing because of the tank location and the use of a controller.

Active and Passive Solar Hot Water System Diagram, image from:

Because I am concerned with just how much water I have been wasting while waiting for hot water, the water efficiency technology I was most intrigued by is the hot water demand/cold water return system. This system works by returning cold water to the heat source, instead of letting it drain, becoming waste water.  I found that the Chilipepper pump website had some of the best explanations on how the method works, so I encourage you to learn more by checking it out.

Basically, when you go to the sink you turn on a pump that begins drawing hot water from your water heater (these work with any type of heating/storage system).   Water going through the pump is returned to the water heater until the pump sensor detects water temperatures above a set temperature.  At this point the pump will turn off and allow the hot water to flow to the faucet.

These pumps also draw water faster than most fixtures, especially new low-flow faucets and showerheads. This means that the outlet will receive hot water much more quickly than without the pump. Also, since the water isn’t being wasted while waiting for it to heat up, you don’t need to be concerned about the high flow rates.

Cold Water Return System Diagram, Image from:

There are so many other ways to save water and improve energy efficiency with hot water. This blog would be way too long if I explained them all!  I encourage everyone to research the topic more.  Point of use water heaters or a tankless heater might be a good way to green your hot water heating system.  The EPA also has a great program called WaterSense, and I encourage you to look at their website; it is filled with suggestions on how to reduce water-waste.  Limiting hot water use, using sustainable methods to heat water and not wasting unused water all help to make a home environmentally friendly. I hope the methods mentioned above are helpful and jump-start your thinking about hot water usage!

Transition from Traditional to Sustainable Engineering Series

November 30th, 2010 by

Hello Readers,

Welcome to my series on transitioning from a traditional to sustainable engineering practice.  I am currently spending much of my time learning as much as possible about sustainable engineering because I feel that it is imperative that today’s engineers begin to incorporate sustainable strategies in all design work.  I hope that through the Sherwood Institute blog forum I will be able to learn and share new information about greener engineering practices.  I plan to write a bi-weekly blog where I can discuss what I learn and hopefully inspire others to increase the use of sustainable design strategies.

I would like to begin by telling readers a bit about my background and how I became so passionate about learning sustainable engineering methods. I received my B.S in Civil & Environmental Engineering from The University of Vermont, where I was taught by very environmentally friendly professors and surrounded by forward-thinking peers.  It was there that I became interested in the environment and how important it is that we practice sustainable design.  A professor (also my adviser) would always say, “Water Bottles are the Devil!”  If you wanted to do well in her classes, you knew ahead of time that you’d better not come to class after stopping to get a Dasani from the vending machine!  When I first started at UVM I thought the majority of these “hippie” professors were a bit crazy.  However, they taught traditional engineering schooling while incorporating sustainable philosophy, and by the time I graduated I guess I, too, had become a bit of a hippie engineer.

The University of Vermont Graduation: I am the one on the right with the purple sash

Upon graduation I went to work in the public sector.  This was a wonderful experience in traditional engineering.  I had great managers and co-workers and was able to gain experience as a project designer and manager. I became more familiar with contract documents, design software and engineering judgment.  My manager noticed my passion for “green” and allowed me the opportunity to become involved in our work to become a more sustainable agency.   This included learning adaptation strategies that will be necessary for key infrastructure as the climate changes, design methods such as green and complete streets and using recycled or permeable pavement.  This experience was especially valuable because it allowed me to see just how difficult it can be to incorporate sustainable practices.  There are many important design standards that have been tested and proven over time.  To not follow these standards can be a scary first step, and sometimes is against local or national policy.  There are also environmental permitting and cost issues that can limit how many new “green” ideas can be incorporated into a project.

While working I took a class at the Harvard Extension School titled “Sustainable Buildings: Design and Construction.” In a multi-disciplinary environment, filled with people with a true desire to incorporate green practices, I learned about topics such as integrated design, LEED, air quality, rainwater harvesting, graywater use, and green roofs.  After attending “West Coast Green 2010” and hearing several incredible speakers including Bry Sarté discuss sustainable engineering, I knew that I wanted to help spread the Green Movement and become a part of sustainable engineering progress.

USGBC LEED Certification: Genzyme Building in Cambridge, MA

I feel it is important both personally and globally to transition to more sustainable practices.  I am a fairly environmentally friendly girl:  I purchase many green products, follow a vegetarian lifestyle, try to use as little energy and water as possible, commute via bike, bus or car-pooling, and carry a Lifefactory Water Bottle everywhere I go.  However, I also enjoy a few luxuries and feel that everyone should be able to indulge a bit and still be a friend to the planet and all of the other people with whom we share it.  At “West Coast Green 2010” William McDonough gave an incredibly inspiring keynote speech.  The message I took home from his speech was that we can not just make the world “a little better” but need to make drastic changes so that we will have enough resources for a rapidly growing population to live luxuriously in both developed and developing countries.

I believe that engineering design must become greener so that we live sustainably and do not deplete the world of valuable resources, so that the world’s inhabitants are living in a healthier environment. We must do this in a way that is not more expensive than traditional engineering options.  Bry Sarté’, in his book Sustainable Infrastructure: The Guide to Green Engineering and Design, sums it all up by saying  “Sustainable design, then, becomes the art of satisfying the same human needs with less energy and materials by increasing efficiency, and also reducing the environmental impact of the energy and materials we do use.”

Over the next several months I hope to learn and share about all things related to sustainable engineering.  I plan to finish reading Sustainable Infrastructure: The Guide to Green Engineering and Design and study for the LEED Green Associate exam.  I want to learn more about integrated design, rainwater harvesting and policies in different countries regarding water re-use.  I am currently living in Lake Tahoe where the “Keep Tahoe Blue” slogan is a very important part of life.  I hope to talk to different businesses about the new Best Management Practices that they need to implement in order to be environmentally friendly.

Beautiful Lake Tahoe- which we need to "keep blue!"

I am sure that as I learn more, new ideas will snowball into in-depth new topics regarding sustainable engineering and water resource management.  I hope that I will learn and share interesting and helpful information for all of our readers and hope to develop a relationship where we can all gain knowledge from each other.  I look forward to hearing your thoughts and ideas. I hope this blog will become a forum where we can all share lots of new ideas!

Looking forward to learning with you,







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