Relative correlations of ARGs (normalised to 16S rRNA) with associated AAs were also investigated (table and). In general, normalising each of the gene targets to 16S rRNA did not change the patterns of gene loads observed across samples. Gene loads were also normalised to the human population of Bath to calculate gene loads per capita; these were positively correlated to gene loads normalised by 16S rRNA (figure ). This observation is an important one. It indicates that the abundance of microorganisms is proportional to the size of human population (as already shown in our previous paper and where strong linear correlation was observed between 16S rRNA and population size: R 2 = 0.8786, r = 0.9373 p value: 0.018657). Our data this further confirm that community size is a major driver of ARG levels in wastewater.