High drinking water temperatures occur due to climate change and could enhance the growth of opportunistic pathogens in drinking water systems. We investigated the influence of drinking water temperatures on the growth ofPseudomonas aeruginosa,Stenotrophomonas maltophilia,Mycobacterium kansasiiandAspergillus fumigatusin drinking water biofilms with an autochthonous microflora. Our results reveal that the growth ofP. aeruginosaandS. maltophiliain the biofilm already occurred at 15.0 °C, whereasM. kansasiiandA. fumigatuswere able to grow when temperatures were above 20.0 °C and 25.0 °C, respectively. Moreover, the maximum growth yield ofP. aeruginosa,M. kansasiiandA. fumigatusincreased with increasing temperatures up to 30 °C, whereas an effect of temperature on the yield ofS. maltophiliacould not be established. In contrast, the maximum ATP concentration of the biofilm decreased with increasing temperatures. We conclude from these results that high drinking water temperatures caused by, e.g., climate change can result in high numbers ofP. aeruginosa,M. kansasiiandA. fumigatusin drinking water systems, which poses a possible risk to public health. Consequently, it is recommended for countries with a more moderate climate to use or maintain a drinking water maximum standard temperature of 25 °C.