How to Make a Water Filter

Jane Marsh - May 11, 2023

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How often do you use water throughout the day? Like most people, you probably shower, brush your teeth, flush the toilet, brew coffee, and run the sprinklers all before 9:00 a.m. We rarely consider water-scarce regions when lugging a case of water bottles home from the store or installing reverse osmosis in the kitchen — unattainable luxuries to those living on less than $2 daily without access to potable drinking sources. Learning how to make a water filter could be a matter of life and death for such individuals. 

A DIY water filter isn’t difficult to construct and is an excellent way to live more sustainably. It could also ensure survival if you get stranded outdoors — a person can only go about three days without water. Here’s everything you need to know to make a water filter at home as this precious resource becomes increasingly scarce worldwide.

6 Steps to Make a Water Filter at Home

Suppose you’ve been harvesting rainwater and want to use it — you must purify it before taking a sip. Even fresh rainwater contains impurities that may harm you. Likewise, if it comes from another ground source, there may be other compounds to worry about.

To make a water filter, you’ll need the following supplies:

  • Plastic bottle with cap — a Gatorade bottle also works
  • Thin cloth filter or coffee filter
  • Activated charcoal, rinsed
  • Fine and coarse gravel, rinsed
  • Sand, rinsed
  • Hammer and nail
  • Large cup for filling the filter with water
  • Large mason jar to catch the water

Once you’ve collected the necessary items, you can follow these steps. 

1. Cut the plastic bottle.

Cut an inch off the bottom of the bottle using a craft knife. This step may be difficult, so laying the bottle on its side and sawing the plastic with the blade may be the best way to achieve this. Just be careful not to cut yourself.

2. Make a hole in the bottle cap.

Puncture the center of the bottle cap with the hammer and nail. A small hole slows the flow of water for more effective purification.

3. Cover the bottle with the coffee filter.

Place a cloth filter over the bottle opening and twist the cap on top. Then, flip the bottle upside down so that it sits in the mouth of the mason jar.

4. Rinse and layer the charcoal, sand, and gravel.

Before you add your filtering substances, make sure they are thoroughly rinsed. Then, pour the activated charcoal into the bottom of the bottle — about one-third. Water treatment plants have utilized activated charcoal since the 1960s and 1970s due to its highly absorbent nature and effectiveness in removing natural organic compounds, synthetic chemicals, and foul odors and flavors.

Then, fill equal parts sand and a combination of fine and coarse gravel, leaving a couple of inches at the cut opening so the water doesn’t overflow. 

5. Pour unfiltered water into the bottle.

With the bottle filter sitting in an empty mason jar, slowly pour your unfiltered water into the opening. The water could take several minutes to flow through the filter into the container. Then, repeat this step with the rest of the water. 

6. Boil the water and cool.

Once your jar is full, boil the water for one minute or longer to eliminate residual contaminants. The U.S. Environmental Protection Agency (EPA) states you must boil water for three minutes if you live 5,000 feet above sea level.

Clean your mason jar, pour the boiled water back into it, and seal it tightly. Allow the water to cool before drinking.

When camping or in a dire situation outdoors, it’s always a good idea to carry water purification tablets to protect you from other bacteria.

Water Scarcity Around the World

Water stress is starting to reach regions many didn’t anticipate, including the United States. According to Water.org, 771 million people struggle to access clean water worldwide, while one in four lacks proper sanitation.

Although water is a renewable resource, climate change and human activity have caused a sharp decline in its accessibility. Most of the earth’s water is already unfit for consumption — deriving from saltwater and polluted sources or locked up in glaciers. Despite freshwater accounting for 2.5% of global water bodies, only 1.2% is available to meet the world’s needs.

Sudan on the Verge of a Water Crisis

Lake Baikal in snowy Siberia, Russia, is 1,700 meters deep and dates back 25 million years. In addition to being one of the oldest lakes in the world, it’s also one of the cleanest — thanks to being highly remote, it’s avoided exposure to industrial and agricultural pollution.

Sadly, Lake Baikal is a far cry from the water quality in developing nations. For instance, only 50% of Sudan’s population has access to potable drinking water, while 10% have their basic sanitation needs met.

Climate change, weak policies, limited funding, and overconsumption spark Sudan’s water crisis. As a result, water scarcity induces conflict, political instability, and food insecurity as rising temperatures in the Sahara Desert dry up moisture and devour agricultural land.

Nima Elmassad — a small-scale farmer — notes that her children had to travel three miles daily in search of clean water for consumption, hygiene, and farming. In 2018, the United Nations Environment Programme (UNEP) and Sudan’s Higher Council for Environment and Natural Resources built a 30,000-meter water harvesting reservoir in Elmassad’s village. While the reservoir has helped farmers in Elmassad’s area, countless other places need similar mechanisms.

The Water Crisis Reaches High-Income Countries

Even the U.S. is feeling the effects of water scarcity across some cities and towns that experience extreme droughts, water pollution, and crumbling infrastructure. From Flint, Michigan, to Jackson, Mississippi, the future of water is uncertain.

Although the U.S. isn’t yet close to enduring a similar water crisis found in the Middle East and Africa, we’ve been somewhat reckless. For example, from 2017 to 2018, scientists found a toxic chemical compound called GenX unique to Chemours — a subsidiary of DuPont — in the bloodstreams of study participants from Wilmington, North Carolina. 

However, substances like GenX — also known as per- and polyfluoroalkyl substances (PFAS) — are everywhere in U.S. waters, as the EPA has allowed numerous industries to go under-regulated. 

Learn How to Make a Water Filter and Conserve

Filtering harvested rainwater at home is an excellent way to conserve water. As climate change worsens drought conditions and populations grow increasingly vulnerable to waterborne illnesses, there must be enough safe drinking water to go around. Learning how to make a water filter at home makes a difference.

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About the author

Jane Marsh

Starting from an early age, Jane Marsh loved all animals and became a budding environmentalist. Now, Jane works as the Editor-in-Chief of Environment.co where she covers topics related to climate policy, renewable energy, the food industry, and more.