We have filtered out particles and crystals from liquids. Now, we will see if we can filter out the stuff we have dissolved in water, to make solutions. We can also try to
filter infusions. That will be fun.

Infusions are easy--I've made some tea and some coffee. We'll just pour it through some filter paper, and then we'll have plain water.

Oops! That didn't work. All we did was make the filters stained with the colors of the tea and coffee, and we still have our infusions. The reason it was so easy is probably
because it wouldn't work anyway.

Okay, let's try it with egg-dye pellets. We'll boil the water, drop in the pellets, and let them dissolve. Shall we use red? We will be able to tell if the solution we've made
can be filtered, because if it works, the filtered water will be clear. If it doesn't work, the filtered water will be red.

Here goes! And, here comes the filtered red water. It appears that solutions cannot be filtered. Filtering apparently works on particles that are in suspension, but it
certainly doesn't do anything for solutions.

This is probably why ground water can be polluted so easily. Dissolved contaminants (say, "conn-TAM-in-unts") just go right through the soil, sand, and rocks, into the water table. Or into an aquifer (say, "AH-kwif-fer").

Now is the time to tell the secret. An aquifer is 'way under the surface of the ground. Most of them are very deeply buried. Some of them are so large, they extend under several states. Aquifers are places in the rock underneath that sometimes have a layer of clay on the bottom, and have huge, thick layers of small rocks, sand, and pebbles on top of the clay. Water seeps down through the soil, and stays in the aquifer until it is full. Then the water may find a way to get out, such as a fracture in the rock on the side of a mountain. The water could come out slowly, like a spring, or it could come out fast, and make a beautiful waterfall. Or, it could even seep into a nearby stream or river. When we drill a well, we often drill right into an aquifer, and the motor on the well pumps the water out for us to use.