My 2c..... I took some time awhile ago to do a 'test' with filtering water. I have a B.S. in Marine Bio so i didn't expect a coffee filter to actually do much of anything. I was completely right. I used some known 'dirty' water and checked it with the microscope. Down to 100x. Many organisms in it. Filtered it through coffee filters.... didn't filter out a single thing. Do NOT rely on the coffee filters to do much more that strain out the big stuff.