When you look at the water balance for a municipality, at how much water is treated to high-quality drinking water standards vs. how much actually ends up in our wastewater treatment system, there is a striking imbalance. Of the treated drinking water in the Los Angeles basin, for example, my numbers suggest that maybe 50-60% makes it to a wastewater treatment facility. Assuming minimal use of off-grid septic systems, where is the other 40-50% going?
The short answer is outdoor water use. Grass and non-native plants require a lot of water to stay healthy, and in our “I have a right to cheap water” mindsets, the water for our plants and cars is not a big deal. Cinnamon McIntosh, a water conservation specialist for Casitas Municipal Water District in Southern California, recently stated that typical overwatered lawns in Southern California receive twice the amount of water as there is rainfall in Ireland. Granted, there’s a lot more evaporation in SoCal than in Ireland, but surely we can do better than this.
Add water scarcity to the equation, and you can understand why water agencies have an interest in water conservation among the people they serve. From paying customers to switch to native plants and grasses to implementing outdoor watering restrictions to price increases, various methods are being tried. Los Angeles has been fairly successful in these techniques, and its per capita water use of 123 gallons per day is the lowest in any US city with a population over 1 million. That said, the LA Department of Water and Power has noticed an uptick in water use this dry winter, especially among single-family homes…which likely points to outdoor water use.
I hesitate to say we should go so far as to jail those who water lawns or wash cars outdoors, but sometimes threat of penalty (the proverbial “stick”) reaches people’s minds more readily than this situation’s proverbial “carrot”: more efficient water use.