Domestic wastewater stored in non-sewered sanitation systems may retain microbiological hazards throughout collection and transport. This study presents a preliminary assessment of a mobile gas–liquid system in which diesel engine exhaust was introduced into domestic wastewater through a diffuser assembly installed in a sanitation tank. The objective was to evaluate changes in the qualitative detectability of Salmonella spp. and intestinal parasite eggs and to screen selected trace metals in wastewater and soil. Two independent laboratory series were considered. In the first series, Salmonella was isolated from untreated wastewater and from wastewater exposed to exhaust for 15 min, whereas it was not isolated after 30 and 60 min. In the second series, Salmonella was present in wastewater collected directly from the treatment plant and after contact with the sanitation tank but was not detected after 30, 60, or 90 min of exhaust exposure. Eggs of Ascaris spp., Trichuris spp., and Toxocara spp. were not detected in any wastewater variant. Concentrations of Pb, Cd, Cu, Zn, Ni, and Hg were determined in the second series. Contact with the sanitation tank was accompanied by increases in several metals, particularly Cu and Zn, but no consistent exposure-time-dependent increase was observed between 30 and 90 min. Soil receiving the exposed wastewater was additionally screened for Cd, Cu, Ni, Pb, Zn, Hg, Cr, parasite eggs, and Salmonella. No systematic increase in trace-metal content with wastewater exposure time was identified. The results indicate a reproducible qualitative transition in Salmonella detectability between 15 and 30 min under the tested conditions. However, the absence of microbial enumeration, experimental replication, exhaust characterization, and analysis of organic exhaust-derived contaminants limits the findings to preliminary screening rather than validation of a sanitation technology.