How To Purify Water With Simple Tools

Published: Jun 21, 2009

With Karin Readel, Senior Lecturer, Geography & Environmental Systems

You never know when or where extreme thirst might occur. Exploring ancient ruins in the Amazon, you drop your canteen into a snake-filled gully. Or you’re hiking in the Appalachian woods, miles from a water fountain.

Or, maybe you’ve always craved a sip of the water in UMBC’s Library Pond. No need to fret. With the help of Karin Readel, senior lecturer in UMBC’s Geography & Environmental Systems program, and her sidekick, Bob the dog, you can have your lake and drink it, too.

— Jenny O’Grady

Step 1: Collect the Water Sample

Be careful not to upset the water unnecessarily. Readel used duct tape to attach an old broom handle to a clean plastic water bottle so she could gain better access to the water at Library Pond. By lightly skimming the top with the bottle, she avoided disrupting the sediment closer to the bottom of the pond. As the saying goes, let sleeping gunk lie.

Step 2: Filter the Water, Part I

If you’re a light packer, you might not have remembered to take coffee filters with you on your trip to the Amazon. If so, a clean handkerchief or paper towel works. Use the filter/hankie/towel to cover the mouth of the metal pot, then pour the water you collected into the pot. You should see bits of sediment collecting in your homemade filter. It’s mostly unicellular green algae, says Readel. Mmmm…algae.

Step 3: Boil the Water

Remove the filter from the top of the pot, and place the pot atop your stove or campfire. Bring your water to a rolling boil that lasts for at least five minutes, if not longer. This is important! Boiling the water kills any major bacteria you might find swimming around, so your belly won’t play host to a parasite circus.

Step 4: Filter the Water, Part II

Once your water cools down, repeat Step 2, this time placing your filter on top of the original bottle and pouring from the metal pot. Be careful not to accidentally place the sediment-laden side of your filter upside-down over the vessel. You wouldn’t want to wash your first round of gunk back into the water, now would you? Yuck.

Step 5: Let it Settle…Then Drink It!

Remember in Step 1 when we told you not to disturb the bottom of the pond? The same principle works here in Step 5. Allow your newly-filtered water to sit for a few minutes, and you’ll notice the remaining sediment falling to the bottom of the bottle. Once this has happened, carefully tip the container and drink from the top of the water. Cheers!

In an ideal world, you might run a simple $2 fecal coliform test on your water before drinking it, like we did in Readel’s lab before the filtration process. However, this isn’t always possible. Please be careful of where you get your water, and always think before you drink.

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