Nearly one third of homes in Minnesota use on-site systems to treat household wastewater. And the number is growing, as baby boomers retire to northern lakes. Many on-site systems, especially in northern Minnesota, don't protect groundwater and nearby lakes from contamination. Now, people are trying new technologies that may cost more but may work a lot better. And health officials are gradually moving toward new ways of monitoring the performance of on-site septic systems. Mainstreet Radio's Stephanie Hemphill reports.