Simple Solar Water Filter




About: I am a photographer and ex-Engineering Student with more than just a curious mind. I use my knowledge about photography and basic engineering to create stunning videos for my YouTube channel (madsciencehacks...

In this instructable , I'll show you how to make a solar water filter with nothing more than a couple of bottles and a short length of PVC pipe.

Here's what you'll need to make this.

  • 2 plastic/bpa-free/glass bottles with screw top lids.
  • One short length of 20mm pvc pipe that's just a bit shorter than the bottles you are using.


  • Drill and 20mm drill bit (or anything else you can use to make a hole)
  • Hot glue gun (optional but not required)

Step 1: Watch the Video!

Watching a video seems to be the way the cool people learn things on the internet but, if you're old-school, you can enjoy reading the written instructions that follow!

If you can't see the video above, find it on my channel here -

Step 2:

Choose 2 bottles about the same size.

I found 500ml plastic water bottles and removed the plastic screw tops in preparation for the next step. (I got these for free- score!)

Step 3:

Once you have removed the screw tops, you will want to temporarily fasten them together using some hot glue. Once they are glued together as shown above, drill a 20mm hole straight through both screw tops.

Although hot glue isn't necessary, it may help to find a way to fasten the screw tops together to ensure that the holes line up perfectly later on.

Once the you've drilled the hole, you can remove any excess glue or leave it on. The glue makes no contact with the water, so it's still 100% safe.

Step 4:

Next, cut the pvc pipe to a length that is slightly shorter than the bottle.

Then press-fit the screw tops onto the pvc pipe and screw on the bottles as shown.

Step 5:

We're ready to test it!

Firstly, we want to make sure we orient the filter the right way. The video below shows this well but you can make reference to the images above to figure it out. Make sure the bottle with the pipe in it is positioned at the top or this filter will not work as described!

Once you know which side is UP ,fill the lower bottle with the water you need filtered and then screw the upper assembly back on.

Leave the filter in the sun for a few hours to a day (depending on temperature). Once enough time has passed, you will find that the water heats up and evaporates through the tube, leaving the dirt behind. The vapor then condenses and clean water collects in the catchment bottle of the upper assembly.

If you liked this instructable, be sure to leave your feedback in the comments section.

If you've read this far and you're still unsure of how this works, just watch the video below or on my YouTube channel.



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    3 Discussions


    2 years ago


    Wonderful design, innovative and inexpensive way to filter water. This will be useful while traveling especially trekking and camping. Helps in reducing the plastic waste at travel sites.

    One question - Since Plastic bottles are harmful especially drinking water from a plastic bottle which is exposed to sunlight for longer times, can we use glass bottles instead of plastic bottles. Kindly advice.

    Thanks In Advance

    S. Ashwin


    2 years ago

    Nice new design!
    On two sidenotes: it's a condensator or still, not a filter.
    And unfortunately BPA is no longer the sole concern, it turns out almost all softeners mess up reproductive vectors in organisms.

    1 reply

    Reply 2 years ago

    Shielding the upper bottle from the sun will help the condensation. Aluminium foil mit be useful to that end as well as to focus light onto the lower bottle to increase evaporation.