1: disinfection step = critical, removes microbial/viral entities. Activated carbon is treated in a way that it is ultra porous. Material who"s surface area is several thousand square meters per gram. The reason it is so high is because of its porous nature. It is full of molecular sized pores and holes. Those holes are the right size to contain small molecules and once they get in they don"t come out they are highly attracted it. It contains these small molecules and very good at filtering molecules. Getting rid of particulate stuff in the water, things that make water cloudy. Colloidal suspension suspension of ultra fine particles called colloidal particles. They have a tendency to not settle on their own, the slightest turbulence will not settle them. They don"t aggregate on their own, they are charged all the same so they repel each other.