A biosand filter is a simple type of water purification system that uses sand, gravel, gravity and some simple engineering to purify water contaminated with biologics and some chemicals. Its structure is generally made of concrete or plastic and is filled with layers of gravel and sand that encoura...By: jimmypat
Continue Reading »
from Instructables: exploring - featured http://ift.tt/1vGJBDw
via IFTTT
