Turning on the faucet and not getting clean water, or any water at all, is a global issue. Cleaning wastewater could help make more water available. In delving into the nuances of wastewater purification, scientists often use computational chemistry approaches. Which is best? Researchers examined five options using 110 reactions associated with a highly reactive sulfate radical breaking apart a contaminant (benzene). They suggest using high-level quantum calculations to spot-check reactions involving the sulfate radical and other inorganic species.