Global Health
Are Wastewater Treatment Plants Representative of Off-Sewer Communities? Edem Fiatsonu* EDEM FIATSONU FIATSONU FIATSONU Syracuse University
Wastewater-based epidemiology (WBE) is widely used to monitor respiratory pathogens, but it remains unclear whether wastewater treatment plants (WWTPs) represent disease dynamics in nearby off-sewer communities. For respiratory transmission, representativeness depends on human mobility linking sewered and non-sewered populations.
Using SARS-CoV-2 surveillance data from New York State (excluding New York City), we quantified epidemiologic alignment between on-sewer and off-sewer communities using weekly incidence (per 100,000) and test positivity. We estimated statewide and county-level in–off correlations and modeled heterogeneity using weighted regression. To identify structural drivers of alignment, we constructed tract-level mobility networks from anonymized Advan data and applied a random-walk–based community detection algorithm (Walktrap) to identify routinely connected areas. We conducted spatial diagnostics to quantify (i) tracts without community assignment, (ii) unstable tracts, (iii) isolated tracts, and (iv) tracts differing from ≥75% of neighbors. Mobility communities were overlaid with WWTP sewersheds and county boundaries.
On-sewer and off-sewer communities showed strong statewide alignment (incidence r≈0.76; positivity r≈0.99), with substantial county-level variation. Higher population density was associated with stronger in–off correlation, while transportation access and vulnerability explained additional heterogeneity. Mobility communities were spatially coherent and often crossed WWTP and county boundaries. Isolated or weakly connected tracts, concentrated in rural areas, showed weaker alignment.
Epidemiologic alignment between sewered and non-sewered populations is primarily structured by human mobility rather than sewer infrastructure alone. Integrating mobility-based spatial methods improves interpretation of WBE and supports more equitable infectious disease surveillance across rural–urban gradients.