Human enteric viruses are present at low levels in sources of potable water. Due to the low minimum infective dose required for such viruses, these low levels are of public health significance and will become more important as water reuse increases. The effectiveness of alum coagulation for virus removal was evaluated using a synthetic water seeded with monodispersed poliovirus LScl. Experiments were done using 10(3),10(4),10(6) Plaque Forming Units (PFU) per liter. A microporous filter concentration technique was used post treatment to increase the virus titer to make possible virus enumeration by plaque assay on BGM cell cultures. Preliminary work was done to determine the efficiency of the concentration technique at 10(3),10(4),10(6)and PFU per liter. An average of 30.9 per cent of the original PFU were recovered. Two coagulation test methods were used at the lower virus titers. In one, virus was added to the system after the coagulant during the flash mix period and in the other, the coagulant was added to water already seeded with virus. Removals were similar for both conditions. Alum coagulation was found to remove 95 percent of the virus present at the low titers. This efficiency of virus removal is similar to that observed at high initial virus titers. Therefore, it appears that alum coagulation is an effective virus removal method. / Master of Science