Microbial contamination in drinking water has become an important threat to human health. There is thus an urgent need to develop antibacterial materials to treat drinking water. Here, porous silver-loaded biochar (C-Ag) was prepared using corn straw as the substrate and silver as the antibacterial agent. C-Ag was then uniformly distributed in polyvinyl alcohol gel beads of eluted calcium carbonate to prepare p-PVA/C-Ag antibacterial composite. The polymer composites were tested by FT-IR, XRD, SEM and TG-DSC. The results showed that C-Ag was more evenly distributed in the PVA gel spheres. Antibacterial experiments showed that p-PVA/C-Ag greatly inhibited Escherichia coli. Practical application tests revealed that p-PVA/C-Ag showed high and sustained bactericidal inhibition and reusability. Generally, p-PVA/C-Ag composite shows high potential to be applied to drinking water treatment.