Catchment prescription data for both Bath and Keynsham was also compared with PNDLs in wastewater (figure ). Interestingly for Keynsham, TET, SMX, and OFX all had months where these were not prescribed by GPs in the catchment area, but the parent AAs, along with SMX metabolite, aSMX, were still quantifiable in wastewater. Looking at average prescribing lengths of these AAs, TET can be prescribed long-term for the treatment of acne and rosacea, both requiring longer treatment times of minimum 12 weeks for acne and 6-12 weeks for rosacea. OFX is used in the treatment of different infections including taken orally for the treatment of urinary tract infections (UTIs), and lower respiratory infections but also can be found in eye drops for the treatment of certain infections. SMX, as previously mentioned, is often prescribed with TMP due to rising sulphonamide resistance rates and the combined synergistic activity. Again, used as a treatment option for a range of infections including respiratory and ear infections. Its use for urinary tract infections is only prescribed alongside bacteriological evidence of sensitivity. OFX and SMX tend to be prescribed in much shorter lengths in comparison to TET (days rather than months). Their detection in wastewater during those periods could be attributed to many reasons, including individuals registered to GPs outside the catchment area, delayed prescriptions (in the case of UTIs) or potential self-prescribing. This does highlight the complexity of estimating community usage from wastewater, but also how using prescription data at face value does not always necessarily give the reflection of what is being actually used in the community. To further investigate relationships between AAs in wastewater and prescribing patterns, correlations between average monthly loads in wastewater with the abundance of AAs prescribed in each catchment per month were investigated. CLR in Bath had strong positive correlation (r value 0.88, p≤0.05) between wastewater loads and prescription data. As previously mentioned, CLR has demonstrated strong seasonal changes, with prescription rates being higher in winter months when compared to summer (figure ). However, whilst catchment prescribing rates for CLR peaked in Keynsham during winter, correlations between prescription and loads were low with no statistical significance (r value 0.19, p value ≥0.05). Keynsham is a commuter town, so reasoning for this could be partially explained due to fluctuating populations with individuals being prescribed AAs in the catchment area but working outside the catchment area in the cities in close proximity. Weaker correlations between wastewater and prescription data could be partially due to the nature of AA prescribing, with shorter courses for some AAs, some lasting days with others lasting months. Whilst prescribing data is an invaluable source of information for identifying prescribing patterns and trends, it does not necessarily give a true representation of how AAs are being used in the community. Items prescribed by a GP could be consumed, stock-piled or disposed of. Furthermore, AA compliance could be a further issue, as previously mentioned one survey identified 1/3 of patients not fully complying to AA treatment with 1/4 admitting to stockpiling of AAs to use at a later date . For AAs that are not stable, and as a result are rarely observed in wastewater (e.g. penicillins), prescription data can give valuable insight. Notably, just because an AA is in low concentration or not observed, it does not mean there is no potential concern with regards to resistance, as low levels could be as a result of resistance mechanisms (e.g. microbial metabolic transformation) to the AA in the bacterial community. Here, metagenomic or targeted gene analysis in wastewater could provide community resistance patterns. WBE is therefore an excellent complimentary technique for healthcare data such as prescriptions, offering a much broader picture.