To enhance the recovery of f(2) bacteriophage and poliovirus by an established method based on the adsorption to and elution from positively-charged Al(OH)(3)-treated silica gel. Polyaluminum Chloride (PAC) was added to water samples to neutralize the negatively charged materials, which can reduce virus recovery by providing a competing adsorption mode on the media surface. Using this improved process (PAC 30 mg l(-1), pH 6.5, temperature 20 similar to 30 degrees C), the recoveries of Poliovirus I and f(2) from small-volume sewage (100 ml) were 110.76 +/- 36.0% and 92.06 +/- 8.65%, respectively (P < 0.05 vs. traditional methods). Recovery from a 20-L volume of sewage averaged 85.65 +/- 4.43% for f(2) and 88.73 +/- 9.76% for poliovirus, significantly higher than the recoveries in the traditional methods (P < 0.05). PAC could enhance concentration efficiency of poliovirus and f(2) phage from sewage water. This method should significantly improve the recovery of viruses from sewage.