Bio-Sand Filter-Long Term, Household

http://www.cawst.org/en/resources/biosand-filter

"The biosand filter has been studied in the field and in labs. It has been shown to remove the following from contaminated water:

Up to 100% of helminths (worms)
Up to 100% of protozoa
Up to 98.5% of bacteria
70-99% of viruses
The filter can also remove up to 95% of turbidity (dirt and cloudiness), and up to 95% or iron (which people often don’t like because it turns water, laundry and food red!). Like other filters, the biosand filter cannot remove dissolved contaminants or chemicals, such as salt, arsenic or fluoride. There is an adaptation of the biosand filter using rusty nails, called the Kanchan Filter, which can remove arsenic from water."