Large numbers of bacteriophagous nematodes Rhabditis sp. were found infesting a distilled water system. Five additional systems were examined to determine if nematode contamination was present in other systems. Two of 6 samples were bacteria infested. A sample from the original nematode-infested system yielded a single live Rhabditis sp. Fungi (one sample), algae (6 samples), and amoeba were also found in the samples.