Hospital wastewater (HWW) is a complex matrix containing nutrients, pharmaceuticals, antimicrobial agents, disinfectants, and microorganisms. Bacteria in HWW readily form biofilms on sewer surfaces. These biofilms develop through bacterial attachment to surfaces and production of extracellular polymeric substances. This lifestyle confers tolerance to wastewater contaminants and facilitates horizontal gene transfer of antimicrobial resistance genes (ARGs). When biofilms are disrupted, resistant bacteria can be released into the environment through combined sewer overflows, representing a significant public health concern. Understanding the spatio-temporal dynamics of bacterial communities and resistomes in hospital sewer biofilms is therefore critical for antimicrobial resistance (AMR) surveillance and mitigation strategies.  We investigated bacterial compositional and resistome changes in sewer biofilms from two hospitals in North Wales across four seasons over one year. Biofilms were collected in situ from hospital sewers. DNA was extracted and analysed using high-throughput qPCR to quantify 96 ARGs and markers, furthermore community composition was characterised through 16S rRNA amplicon sequencing. Biofilms were also cultured on selective chromogenic media targeting ESBL- and carbapenemase-producing Enterobacteriaceae, methicillin-resistant Staphylococcus aureus, and vancomycin-resistant Enterococcus spp.  Significant clustering of spring samples was observed in for both community composition and resistome profiles.  Additionally, marked spatial variation was detected, with the two hospitals showing distinct clustering patterns. Among the targeted genes, only three were undetected, indicating widespread ARG prevalence. Culture-based analysis revealed varying levels of resistant bacteria, with no significant differences between hospitals. These findings demonstrate substantial temporal variation in hospital sewer biofilm characteristics and highlight their role as AMR reservoirs