It is not often that a desk-bound policy wonk can grab the attention of a pre-schooler by talking about her day, but I have found a new way to connect with my four-year-old twin boys: toilets, and where stuff goes when you flush them.

To be more specific, my work recently has dealt with septic tanks and their challenges. The fascinating world of state sewage regulation got even more fascinating last summer when Maryland’s Task Force on Sustainable Growth and Wastewater Treatment gathered to work through the complex relationship between septic systems, sprawling subdivisions, and the health of the Chesapeake Bay.

Maryland’s Department of Planning estimates that each new household that relies on a septic tank will generate about 23 pounds of nitrogen per year, compared to just 2.5 pounds per household connected to a wastewater treatment plant. If the coming decades’ growth follows current trends, roughly 26% of new households coming to Maryland will rely on septic systems. That quarter of the population will be responsible for three-quarters of the future nitrogen pollution load. What’s so bad about nitrogen? When it leaches into soil and drains into the Chesapeake Bay, nitrogen encourages the growth of algae that use up oxygen and block out sunlight, eventually creating dead zones.