Conserving Indoor Water


Fewer opportunities than you might think to save more water indoors There's lot of talk these days about water conservation and the need for everyone to do their part.  With the ever-present drought in Texas, many communities are feeling the pinch of dwindling water supplies and the lack of rainfall to replenish these water supplies.

Cities spend a lot of money on educational campaigns to teach people ways to conserve water.  Why do they do this?  They want to prolong the potential investment in the “next” water source for their community.  Developing a new source of water or extra water treatment capacity is very expensive for cities.  Just look at the cost for the new Water Treatment Plant #4 in Austin -- an estimated $508 million (not counting interest).

Conservation is much cheaper and is always the first option that city and state planners look at in order to maximize the use of their existing water infrastructure and investments.  While cities look to water conservation first, achieving the desired (and assumed) results can be very elusive.

Educating people about water conservation is great, but in the end, the people have to go home and actually implement the changes to their households and lifestyles.  To see water savings, city planners now have to count on us to take shorter showers and turn turn off the water while we brush our teeth.

So if it's tough to rely on people to make a lasting change in their water-use patterns, why don’t we just increase the efficiency of our indoor water fixtures so they use the least amount of water possible?

Well, take a look at the following graph.  It shows the progression of water use standards by toilets, dishwashers, and clothes washers over time.  As you can see, the water fixture manufacturing industry has made amazing strides over the years, mainly due to the U. S. Environmental Protection Agency’s water-use standards for water fixtures.  All new building projects must install water fixtures that meet a minimum water-use standard set by the EPA.


What should you take away from this?

Well, if you look at the extreme right of the graph, you can see that we don’t have much more room to reduce water use by indoor water fixtures. I mean, while reducing toilet water use from 1.6 gallons-per-flush (gpf) to 1.2 gpf is admirable, it's only a 25% increase in efficiency. Contrast this with the previous drop from 3.5 gpf to 1.6 gpf, a 54% efficiency increase. We have the law of diminishing returns at work here. That law says that in all productive processes, adding more of one factor of production while holding all others constant will, at some point, yield lower per-unit returns. In other words, the more money we spend trying to conserve water with the “next edition” of a water fixture, the less water savings we will achieve in comparison to previous editions.

So now we are back to relying on us to affect real water savings. If our water fixtures can’t be made that much more efficient, the onus is now on us to change our water-use habits. I would estimate that many of you reading this blog post already do your part to reduce your indoor water use by taking short showers, washing dishes only when the dishwasher is full, turning off the faucet when you brush your teeth, and so forth.

So how can we achieve the next water conservation goals city and state water planners need? If our water fixtures are already efficient, and we’re minimizing the time we use a particular indoor water fixture, how can we save more water? The answer is outdoor water conservation. It’s the great, untapped savior for water conservation planners.

Why would outdoor water conservation have a big impact? Did you know: On a summer day in Austin, more than 50% of the water that’s used goes to outdoor irrigation.

As you can see, we have the greatest opportunity to reduce our water consumption, especially during our dry summer months, by changing our outdoor water-use habits instead of focusing on our indoor water-use habits.

In the next post in this series, I’ll delve into this issue more and provide some solutions. For now, take shorter showers, and start looking at how you use water outdoors and imagine ways to reduce your water use there.

Until next time, Chris

Chris Maxwell-Gaines, P.E., is the co-owner of Innovative Water Solutions LLC.  IWS is a design / build company that specializes in water demand and supply management in residential and commercial projects. They create rainwater harvesting, graywater reuse, and irrigation systems as well as drainage improvements and landscape solutions throughout central Texas.

Visit their web site and read their blog.