On the basis of the many postings in the Rainbow Water Coalition, it should come as no surprise that I voted against treating the kitchen sink wastewater. No one in the group cared to ask why, but my reasoning has been clear from the onset of the advisory group process. Where we will find the "greywater-o-meter" that will indicate the treated water is "safe"? What processes will be acceptable, and what will be the "metrics of success" in the treatment process? All of this wrapped up in - "what will the casual greywater reuser be willing to do to ensure "safe" treatment?"
More importantly, it was never very clear what the risk was to "protect the public" - something that I was tacitly accused of not being sensitive to when I did not join the coalition in voting. The advisory committee has a toxicologist from a state agency onboard to help with the process. During past meetings, the toxicologist presented an interesting list of chemicals and microorganisms that have been documented in greywater derived from the peer-reviewed literature. What was missing from the analysis was the apparent source of the various threats - our homes. Yes, we are exposed to these threats in our homes - the greywater is simply the transport mechanism to move these threats from inside our homes to the outdoors. Consider what I call the "Brita Filter Conundrum" - the Brita Filter is purchased by a consumer to "treat" the tap water for a variety of things they think are hiding in the tap water. But the Brita Filters don't last forever. If not changed on a regular basis, say every four to six months, bacteria become trapped in the filter. So, what has been purchased to make water "safer" has actually caused the water to become less safe. The Pogo Syndrome: "We have met the enemy... and he is us".
The second, and perhaps more important, facet missing from the analysis was a risk analysis or assessment; the bread and butter of toxicological work. The toxicologist was not asked to provide these analyses by the group so it was not an omission. But it is an important next step in assessing whether or not greywater is truly a threat to our wellbeing since it comes from us to begin with. And some members in the audience also wanted some more "facts" regarding some statements they heard during the meeting.
What is the risk to our wellbeing from greywater, and specifically kitchen sink wastewater? Art Ludwig of Oasis Design, perhaps one of the foremost experts in greywater reuse in the western US, and perhaps in the world has explored this issue. Oasis Design asks the question - If you irrigate your fruit trees with kitchen sink water, how likely is a kid to get sick from eating the dirt under the trees?
I will paraphrase their analysis given that the answer they provide might offend those readers who are sensitive to the kitchen sink wastewater issue: "A risk assessment analysis of this scenario is viewable in the Arizona greywater study (can be viewed at the Oasis Design website). Note that they assume from the high level of indicators that there is a level of pathogens in the water corresponding to nearly a gram a day of fecal matter entering the kitchen sink. This could be accounted for by ten people (cleaning themselves after defecating) with their hands only and washing them off in the kitchen sink—an unlikely scenario, I dare say. (If nothing else, few houses have ten people in them!) Also, note that they assume that 100% of the dirt the child eats will come from the greywater-irrigated area, 365 days in a row."
"Considering that even with these wild assumptions, the risk was on the order of 1 in 10,000 of the kid getting sick, the risk is probably not significant."
For comparison, let's look at the risk of attacks from the natural order compiled from How We Die:
Risk of death from botulism 1 in 2,000,000
Risk of death from fireworks 1 in 1,000,000
Risk of death from tornados 1 in 50,000
Risk of death from airplane crash 1 in 20,000
Risk of death from asteroid impact 1 in 20,000
Risk of death from electrocution 1 in 5,000
Risk of death from firearms accident 1 in 2,000
Risk of death from homicide 1 in 300
Risk of death from automobile accident 1 in 100
What is the problem?
Wisconsin determined that treatment of greywater was counterproductive to reuse - nobody thought they could do it based on complex regulations. Australia found that overregulating of greywater reuse also lead to unintended consequences.
Next posting, The Greywater Gauntlet....