A comparison of machine-assisted chemical disinfection, using a glutaraldehyde solution, and machine-assisted hot water disinfection was made by placing a large inoculum (approximately 10(7) colonies of Pseudomonas aeruginosa or Acinetobacter calcoaceticus var. anitratus) in sets of tubing before processing. Machine-assisted chemical processing proved to be the most efficient method with a disinfection failure rate of 6 per cent (two positive tubes out of 35). Machine-assisted hot water processing had a disinfection failure rate of 83 per cent (44 of 53 tubes were not successfully disinfected). Some of the tubes that were disinfection failures were dried in a hot air cabinet after the initial sampling, which further reduced the colony counts in the tubing but did not totally eliminate growth except in one tube. The colony counts after drying, showed that A. anitratus was 15 per cent more sensitive to hot air drying than Ps. aeruginosa, but this was not a statistically significant reduction.