#3-7, p. 23

3.
a. manufacture of the filter paper: indirect
It is indirect because the water is not intentionally used for the manufacturing of the filter paper. We also can not determine how much water was precisely used. You also do not directly use the water for the end product of the paper.
b. pre-moistening of the sand and gravel: direct
It is direct because the water is obtained and poured into the lab. We intentionally used the water directly for a purpose and we could easily calculate how much was used.
c. use of water to cool the distillation apparatus: direct
It is direct because the water is used specifically for one purpose: to cause the evaporated pure water vapor to condense back into water. We also come into direct contact with it and also can calculate how much we used.
4. Purifying water means to make water pure. This means free of all toxic matters, odorless, free of solid matter, oil, and chemical properties that could be dangerous if consumed. The purest form of water is distilled water.
5. Three techniques that can be done to make water cleaner are oil-water separation, sand filtration, and charcoal adsorption/filtration.
6. In oil-water separation, most of the oil from the surface of the water was removed. In sand filtration, the water came out slightly cleaner, and free of mostly all solid matter  except for a few tiny grains of sand. In charcoal adsorption/filtration, the charcoal absorbed the small impurities and almost completely got rid of the odor. The final product after charcoal adsorption/filtration was completely clear.
7. It could not make it suitable for drinking water because the water still had salt. Drinking water for salt could easily make someone sick. This was proven by an electric conductivity test, displaying a lit light bulb resulting from the conductivity of the salt water. A necessary additional step in order to make the water drinkable would be distillation. Distillation evaporates the water in its pure state, leaving all the salt behind.