Large-scale, scientist-led, participatory science (citizen science) projects often engage primarily participants who are White, wealthy, and well-educated. Calls to diversify contributory projects are increasingly common, but little research has evaluated the efficacy of suggested strategies for diversification. We engaged participants in Crowd the Tap through facilitator organizations like Historically Black Colleges and Universities (HBCUs), predominantly White institutions (PWI), high school science classrooms, and corporate volunteer programs. Crowd the Tap is a contributory project focused on identifying and addressing lead contamination in household drinking water in the United States. We investigated how participant diversity with respect to race, ethnicity, and homeownership (a proxy for income) differed between participation facilitated through a partner organization and in unfacilitated participation in which participants came to the project independently. We were also interested in which facilitators were most effective at increasing participant diversity. White and wealthy participants were overrepresented in unfacilitated participation. Facilitation helped increase engagement of people of color, especially Black households, and lower-income households. High schools were particularly effective at engaging Hispanic or Latino participants and HBCUs were important for engaging Black households. Ultimately, our results suggest that engagement through facilitator organizations may be an effective means of engaging diverse participants in large-scale projects. Our results have important implications for the field of participatory science as we seek to identify evidence-based strategies for diversifying project participants. 

The data was collected through an IRB approved survey in which Crowd the Tap participants submitted data on the types of pipes they had, the age of their home, water aesthetics, and demographic information. As part of this process, participants also indicated if they came to the project through a partner organization (what we call facilitator organizations). We used information on reported types of facilitators, race and ethnicity, and homeownership (as a proxy for income) to investigate how diversity differed across facilitation.