Consumers are becoming more aware of the contaminants, like nitrates, in drinking water. That leaves a huge opportunity for companies to purify water without the use of chemicals. One such company is HydroNovation, based in San Francisco. It makes residential and commercial water treatment systems that use a chemical-free process called electrodeionization to soften and purify water. In January, HydroNovation landed an investment from 3M New Ventures.