A new study in nine cities examined the life cycle analysis of swimming pools. Inputs, included electricity, water and pool chemicals. The environmental impact is worse in cities like Phoenix that have little water and use coal-fired electricity. The operating inputs in Phoenix involve on average 30,000 gallons of water per year, 22% of the household energy use, and evaporation of chlorine-based pool chemicals that can cause local ozone problems. Comparing the impact of the pool in terms of water, energy consumption and greenhouse gas generation, it is clear that the best place in America to have a swimming pool is Seattle, where there is minimal evaporation of water and clean hydropower running the pumps.