An investigation into the antibacterial properties of silver, copper, aluminium, zinc, brass, bronze, tin and silicon, in combating coliform bacteria in contaminated water has been carried out. The metals, in the form of thin plates, were immersed in water samples at various time intervals at room temperature (~20^°C). Total coliform and Escherichia coli (E. coli) enumeration was done on the samples, before and after immersion, using 3 M Petri films. The results show that copper, silver and zinc in group I and II of the periodic table of elements have the highest rate of destroying the bacteria, followed by aluminium in group III, and the least reaction was in tin and silicon, both in group IV. These results indicate that the antibacterial activity of materials depend on the group they belong to in the periodic table; the higher the group the lower their efficacy. No direct relationship has been found between the metal activity and ionisation energy.  An interesting observation was that zinc was as effective as copper in destroying the bacteria.  It was also found that the more the surface area of the metals, the faster they destroyed the coliforms. Practical applications of the results are outlined.

Key words: Metals, alloys, coliforms, Escherichia coli.