Straw Filter

(Photo: Btrevett on Appropedia, CC BY-SA 3.0)

Having an instant source of drinking water anywhere you can find water is a hard thing to come by in the developing world and while out backpacking in nature. This 3D printable straw filter should allow for cheaper and more readily available access to clean water at a lower price as most of the components of a water filter are things we come across every day. The main components of most survival water filters today are gravel, sand and activated carbon. These three things in addition to a cloth of some sort to keep the described things from going into our water are what make up a water filter that will filter out most of the harmful things.

(Photo: Btrevett on Appropedia, CC BY-SA 3.0)

Fig 1: Assembled Straw Filter

(Photo: Btrevett on Appropedia, CC BY-SA 3.0)

Fig 1a:Straw Filter 3D printed parts

(Photo: Btrevett on Appropedia, CC BY-SA 3.0)

Fig 1b: Straw filter 3D slicer/print orientation

Bill of Materials

• 3D printed bottom of the straw: Estimated cost is $0.62 based on 20$ for a 1kg roll of filament and an approximate use of 31g for the print.
• 3D printed top of the straw: Estimated cost is $0.30 based on 20$ for a 1kg roll of filament and an approximate use of 31g for the print.
• 1 inch O-ring $0.11 from amazon [1]
• Sand from the beach sterilized with hot water $0.00
• Small pea gravel sterilized with hot water $0.00
• Activated carbon: Estimated cost $0.38 based on $6.52 cost for 255g from Walmart and an estimate use of 15g. Alternative cost should be $0.00 from burning wood.
• Piece of cloth to keep materials in straw: $0.00 any piece of cloth laying around should work. Alternatives could include coffee filters or a purchased washcloth. 100 coffee filters for $1.50 from Walmart. Washcloths could be ordered from amazon $15 for 24 washcloths and only a small piece of the washcloth would be needed so the cost would be less than $0.10 per straw. [2]

Source Files

Source files can be found on youmagine here: [3]

Tools needed for fabrication of the Straw Filter

• MOST Delta RepRap or similar RepRap 3-D printer
• Fire for boiling water sterilization of parts and creation of activated carbon

Skills and knowledge needed

• If you used special skill – link to relevant wikipedia or wikiversity articles/courses

Technical Specifications and Assembly Instructions

Rinse all materials in boiling water before adding them to your filter.

(Photo: Btrevett on Appropedia, CC BY-SA 3.0)

Step 1 add pea gravel to bottom of straw

(Photo: Btrevett on Appropedia, CC BY-SA 3.0)

Step two add sand to straw

(Photo: Btrevett on Appropedia, CC BY-SA 3.0)

Step 3 add activated carbon to straw

(Photo: Btrevett on Appropedia, CC BY-SA 3.0)

Step 4 roll up cloth of some kind

(Photo: Btrevett on Appropedia, CC BY-SA 3.0)

Step 4 roll up cloth of some kind

(Photo: Btrevett on Appropedia, CC BY-SA 3.0)

Step 5 insert cloth into straw

(Photo: Btrevett on Appropedia, CC BY-SA 3.0)

Step 6 Add O-ring to straw top

(Photo: Btrevett on Appropedia, CC BY-SA 3.0)

Step 6 Add O-ring to straw top

(Photo: Btrevett on Appropedia, CC BY-SA 3.0)

Step 7 screw in the top to the bottom and enjoy

• Print time estimate: 3.5 hours total, 2.25 hours for bottom and 1.2 hours for the top.
• Assembly time estimate once all materials have been gathered: 3-6 minutes.

Print Settings

Filament feed rate: 105%
Print temperature for PLA 210C

*Top of straw filter

• Layer height: 0.2mm
• Wall line count: 4
• Top and bottom layers: 4
• Infill density 25%
• Overlap percentage 10%
• Print speed: 50mm/s
• No print support needed
• Build plate adhesion: brim or skirt

*Bottom of straw filter

• Layer height: 0.2mm
• Wall line count: 4
• Top and bottom layers: 4
• Infill density 100%
• Overlap percentage 10%
• Print speed: 50mm/s
• No print support needed
• Build plate adhesion: brim or skirt

Common Problems and Solutions

• In slicing software rotate the top of the straw filter 180 degrees so that the threads are facing up to allow for a perfect print.
• Also in slicing software scale the top to 98% to allow a 2% tolerance for the threads.

Cost savings

• Estimated cost of total device: $1.41 from the Bill of materials above.
• Commercial equivalent costs $19.99 from Dicks Sporting goods [4]
• $19.99 - $1.41 = Cost Savings of $18.58 and a 92.94% savings.

Benefited Internet Communities

• Charity: water [5]
• Water.org [6]
• Columbia water center [7]
• WATERIsLIFE [8]
• The water project [9]

References

• How to make a survival water filter: https://www.wildernessawareness.org/articles/how-make-survival-water-filter

Where this page came from

This page was imported from Appropedia. “Straw Filter” from Appropedia, by its contributors, under CC BY-SA 4.0. Changed here: set as a page; the project databox, notices and edit links left out; each photo under its own licence, credited in its caption.

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