Does the biosand filter remove all bacteria and viruses?
The biosand filter will remove over 95% of bacteria and 80-90% of viruses, if the filter is properly installed and used. In most cases, the amount of bacteria and viruses that pass through the filter will not be enough to make a healthy adult sick. Young children, the elderly, people living with HIV/AIDS and sick people are more vulnerable to the bacteria and viruses. CAWST has prepared a summary of laboratory and field studies for the biosand filter.
