Low pH and high lactic acid concentration of fermented feed has been reported to be responsible for the antimicrobial activity of fermented feeds (Brooks et al., 2001). For example, to prevent the growth of Salmonella spp. in liquid feeds, a threshold lactic acid concentration of 75mM is required (Beal et al., 2002). Therefore, factors that are likely to affect the production of lactic acid during fermentation will have important implications for the ability of such feeds to withstand colonisation by pathogens. The objective of the present study was to investigate the effect of water quality on the fermentation pattern of sorghum and barley.