How To Make a Tap Water Filter

Of all the tap water filters on the market today, by far the most common is a filter made from activated charcoal, and for very good reason. Activated charcoal has been used for centuries for purification of water, air, and food, as well as for medicinal purposes.

Buying a tap water filter system, and continuing to purchase replacement water filters can be expensive. Here is a simple and inexpensive way to make your own tap water filter system, using items that you can easily buy locally or online.

Materials Needed:

  • 1 Liter Plastic Bottle
  • Drill
  • PVC Glue, 100% Silicone Sealant, or other nontoxic glue
  • Coffee Filter
  • 1 Quart Activated Charcoal

  1. Activated charcoal can be purchased at a local aquarium supply store, or online at  The best activated charcoal to use for a water filter system is Granular Activated Charcoal (GAC) that has a granule size of 8x16 mesh or smaller.
  2. Begin by drilling a hole in the bottom of the water bottle, just slightly larger than the diameter of the plastic straw.  Insert the end of the straw into the hole and glue it in place, so that the end of the straw is even with the bottom of the bottle, and the straw is extending out of the bottom.
  3. Insert a coffee filter so it is flat across the bottom, then add the activated charcoal.
  4. To use the water filter, simply insert the straw into a container, then pour tap water through the top of the bottle, so that it drains through the charcoal and into your container.

Activated charcoal best absorbs impurities when the tap water is cool, rather than hot, and when it travels through the water filter slowly, rather than quickly.

Allowing your new tap water filter to dry out between uses will help to prevent bacterial growth.

Your charcoal will eventually become saturated with contaminants. Make sure you replace your charcoal at least every 3 months for best results. If your filtered tap water ever begins to taste bad or different than usual, change the charcoal in your water filter.

Although a home-made charcoal tap water filter system can remove a large variety of contaminants from your tap water, it is not guaranteed to remove fluoride or organisms such a Giardia sp. or Cryptosporidium sp. You can check with your local water company to determine if an activated charcoal tap water filter system will meet your water filtering needs.


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