MICROBIOLOGY OF THE SPACE-SHUTTLE WATER-SYSTEM

The Space Shuttle has a once-through water system that is initially fi lled on the ground, partially drained before launch and then refilled with fuel-cell generated water on orbit. The microbiological standard for the Space Shuttle potable water system during this study period al lowed only I microbe of any kind per 100mL and no detectable coliforms . Contamination episodes in more than 15 years of Shuttle operation ha ve been rare; however, for the past 24 missions, bacterial contaminati on has been detected in 33% of the samples collected 3d before launch. These samples have had on average 55CFU/100mL of bacteria, with the m edian less than ICFU/100mL. Burkholderia cepacia has been the primary contaminant of the Shuttle water supply system both before and after f light. Water samples assessed during the STS-7G mission aboard the Spa ce Shuttle Discovery were found to be contaminated (<20CFU/100mL) with B. cepacia and B. pickettii. In 1991, waste and water lines were remo ved from the Space Shuttle Columbia and the waste lines were found to harbor biofilms containing Bacillus spp. Nevertheless, the water syste ms of the four Space Shuttle vehicles provide extremely pure water. (C ) 1997 IAWQ. Published by Elsevier Science Ltd.