29 July 2013

Recycle reuse reduce?

When it comes to consumer goods, reduce-reuse-recycle makes lots of sense. Don't buy that bike if you're not going to use it. If you are going to use it, then reuse a used one. Once you're done using it, recycle it instead of dumping it into a canal (the Dutch option :)

That consumer-centric logic may make sense for private goods, but it may not make sense with water, a collective good for which "use" has a larger definition.

Consider the low flush "green" toilet. Most people consider the water "used" when it's flushed down the toilet. Under that belief, it makes sense to "reduce" water use by installing a low flush toilet, but such an installation may not make sense when the sewer system needs lots of water to "flush" through solids, if the treatment plant works better with a higher liquid:solid ratio and/or if the treated water can be reused or even recycled (yes, toilet to treatment to tap). Under those conditions, low flush toilets may deliver worse results for the consumer who has to pay for the new appliance (they last for decades) or for the utility that needs to spend more time or money (a cost that's passed to customers, of course) to adjust to lower water volumes.

Bottom Line: Don't just look at the isolated impacts of an action or policy -- consider them from start to finish.


  1. I think this is a good insight.

    Low flow toilets have created old toilet disposal problems and consumer use problems. The regulatory approach of reducing water use by focusing one this single aspect appears short sighted.

    Bottom Line: I think I would much rather pay for the additional gallon used per flush than deal with the other consequences.

  2. Coming from the other side, laws and management processes need to consider the physical processes of the systems that they are set up to govern. Just like there is short-sightedness in product design vs. system needs, there is short-sightedness in legal water conservation frameworks themselves vs. the water systems they are set up to manage.

    For example (unless the law was changed), in Colorado, it's illegal to install rain barrels and use collected rain water for irrigation, since these were considered diversions or takings under the prior-appropriation doctrine that undergirds Colorado state water law. Further, SCOTUS rules back in 2004 (or so) that there is no such thing as a "water nexus", maintaining the legal precedent of separating groundwater and surface water (even though science has advanced to a point where connections between surface and groundwater can be demonstrated and modeled).

    In both cases, the outcomes of maintaining legal precedence over physical process has led to water management problems that are shifted to become externalities.

    Bottom Line (#3): Governance structures need to consider they systems they are set up to govern, and not get trumped by precedence (especially when precedence can be proven to be incorrect or insufficient).

  3. Bravo,

    This in a nutshell is the problem with low flow toilets or even high efficiency irrigation. The extra water being used serves a purpose and if that water is not flowing then there may need to be mitigation....the least costly of which is ususally using the "saved" water to maintain the lost flow....but that the law may say is a waste of water.

    If the impact is higher TDS, then desal becomes the only other mitigation option....which nobody includes in a CBA of water savings and efficiency upgrades.

    So in some cases the "saved" water is used to enable new development or added acres of production with the above resultant desal or waste handling cost put on everyone to deal with ....later.

    Alternatively if the ones who covet the "saved" water would instead develop it directly (ie desal) than the full cost would be on them.

    Also as a wastewater guy I can say one should strive to consider the water cycle impacts from finish to start, not visa-versa, as the finish line is something people tend to give short shrift, or delay dealing with...ie the irrigation system in the Central Valley of California. As hard as water supply projects are to engineer correctly, the hardest and most consequestial work is ususaly at the tail end.


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