Drinking enough water is one of the most important factors for good health. However, drinking water from plastic bottles and drinking tap water both have their disadvantages. One of the most ecological solutions is to filter your own tap water. You don't even have to buy a ready-made commercial filter system because you can just as easily make your own water filter at home.
Choose a big clear bottle or container for the filter. You can use a 2-liter plastic bottle. Cut out the bottom of the bottle completely using a sharp knife or scissors. Then drill in a small hole on its plastic lid. This bottle will be the body of your water filter.
Place a coffee filter or cotton batting on the inside of the bottle neck. This will be the last segment of your water filter. It will also hold all the particles from the filter layers. Completely cover the opening of the bottle with the coffee filter to get the best results and the purest water. You can use a nontoxic glue to glue the coffee filter's edges to the bottle.
Turn the bottle upside down. The bottom part should be the bottleneck. Put a few spoons of diatomaceous earth and spread it around the filter. This will be the first layer above the coffee filter.
Place another filter layer of activated charcoal on the top of the diatomaceous earth layer. This will be the second layer of your filter.
Pour fine-grain sand on the charcoal layer. The layer should be at least 2 inches. Then pour a layer of large-grain sand over the layer of fine-grain sand.
Pour a layer of fine gravel over the layer of sand. Then pour a layer of large gravel on top of the fine gravel. Make sure to pack at least 2 inches for each layer in order to fill out the whole filter.
Insert a straw or a wine pour cap into the hole of the bottle lid that you made in Step 1. Position the filter over a large glass or a narrow container. This way, the water you pour into the upside-down bottle will slowly make its way through all the layers and through the coffee filter, imitating the way water is filtered in nature, going through different rock sediments and clay.