Introduction: Adjustable Water Bottle Filter (prototype)

"Americans throw away 35 billion empty water bottles a year. Of those, only 12 percent are recycled" (Healthy Human). Bottled water is incredibly useful for people both on the go and away from home. Despite its negative impact on the environment, many people find themselves using bottled water when they have no other access to filtered water. Furthermore, even when filtered water is easily accessible, depending on the location it may taste vastly different than what you may be used to. Leading people to further rely on water bottles for tasteless water.

In an effort to curb the excessive use and disposal of plastic water bottles, I made a basic filter for plastic water bottles that is adjustable to the different mouth sizes of water bottles. Therefore, a bottle can be refilled with filtered water (with an unfortunate taste) and that taste can be removed. 

Given that you own a 3D printer, this build is extremely cheap and uses previously used water bottles and a few other objects you likely already own. In total, I spent 6 dollars to make this prototype. The filter I made was based on an easy water bottle filter that can be made for emergency filtration of dirty water. There are many alternate filters that can be created using this system, which would make the filter more effective. Including rocks, sand, and grass. These additional layers can remove organic materials including pathogens and suspended solids. However, since improved water taste was the main goal of my filter I only utilized activated carbon. 

My Design requirements were:

  • Under 10 dollars to make
  • Can remove the taste of Tap water
  • Can be used to fill multiple different bottle mouth sizes


AN IMPORTANT NOTE:

A carbon filter's ability to remove contaminants depends upon the filter's micron rating. Most carbon filters can not remove acceptable amounts of lead, iron, arsenic, cysts, and coliform bacteria. Unless they are rated at one micron or less (meaning they have a very small pore size. (ESP Water Products).

“However, an activated carbon filter will remove organics that can affect the taste, odor and color of your water, and reduce chlorine, THM, pesticides, industrial solvents, polychlorinated PCBs, PAHs, and radon gases” (Spiridakis).

Therefore while I can not recommend the consumption of previously untreated water. Given that the water is previously filtered, this filter is a good resource if the given water still has an unacceptable taste. And can function to further purify water from harmful chemicals.


Now that the warning is out of the way, let's be safe and make an adjustable water bottle filter!





References:

Plastic water bottle pollution: Where do all the bottles end up? Healthy Human. (n.d.). Retrieved April 23, 2023, from https://healthyhumanlife.com/blogs/news/plastic-water-bottle-pollution-plastic-bottles-end#:~:text=Americans%20throw%20away%2035%20billion,of%20bottled%20water%20a%20year.

Spiridakis , N. (n.d.). What do carbon filters remove from water? . LIVESTRONG.COM. Retrieved April 23, 2023, from https://www.livestrong.com/article/193977-what-do-carbon-filters-remove-from-water/

What does activated carbon filter remove. ESPWaterProducts.com. (n.d.). Retrieved April 23, 2023, from https://www.espwaterproducts.com/what-do-carbon-filters-remove-from-water/#:~:text=Some%20carbon%20block%20filters%20rated,%2C%20cysts%2C%20and%20coliform%20bacteria. 
















Supplies

The materials that your going to need are,

  • 2 Empty Water bottles, (one with similar dimensions to an Aquafina bottle.)
  • 3/4 Cup Activated Granulated Carbon
  • Coffee Filter
  • 3D Printer
  • PLA Filament
  • Rubber Bands
  • Water (preferably filtered)
  • Circular Small Funnel

Step 1: Coming Up With the Idea / Measurements

(Coming up with the idea / Measurements)


My first idea was to purchase a water bottle filter and attach a clamp on the bottom of it so it could fit multiple water bottles however I ran into some problems with this design idea. First, the small connection piece to the bottle would likely not provide enough support for the top filter, causing the design to tip over very easily. Also, there would need to be a much larger area for water on the top of the filter to hold the access water as it slowly travels through the filter. This is why I then opted for a cup-holder-type design with screws at the bottom to both center the cupped filter with the mouth of the fillable bottle and to clamp the fillable bottle to make sure it doesn't move. The filter holder was designed for an average-sized water bottle (about 2.5 inches in diameter). I sized the fillable bottom to at most fit a Gatorade bottle cap (around 1.5 inches). Given the hanger screws any mouth smaller than that size should be able to be filled.

Step 2: Printing the Parts



First, use a 3D printer to print the Bottle Holder and the hanger screws. I created the bottle holder on Solidworks and sourced the hanger screws from McMaster-Carr. You can find the STL files attached.

You will need to print

1 Bottle Clamp

2X Hanger Screws

Printing details:

Slicer: Cura

Quality: .20mm

Infill: 15%

Supports: (only for screws)

Speed: 60 ppm

Rafts: Yes

Scale: (100% for Bottle Clamp) (95% for hanger screws)


After printing the design I realized that one screw would push the mouth to the side when fully clamped which would cause problems for the funnel which I planned to be centered. Thus I added another hole on the opposite side of the bottle clamp to center the fillable bottle. Therefore, to ensure the bottle is centered you will need to print 2 screws.

Attachments

Step 3: Building the Filter


Parts:

  • Empty water bottle
  • Rubber bands
  • Coffee Filter
  • Activated Carbon (crushed)

Tools:

  • Scissors
  • Screw Driver


In order to build the filter simply wrap a coffee filter around the mouth of the filter bottle and secure it with rubber bands. Then crush your activated carbon into medium-fine particles. And dump the crushed carbon into the filter with the secured coffee-filtered end. You can then take the cut-off portion of the water bottle and use that as a stopper to secure the crushed activated carbon. Simply poke multiple small holes into the back of the water bottle (I used a small screwdriver). And press the filter stopper as far down into the water bottle as it will go. Congratulations you have a very basic water filter.

Step 4: Putting It All Together


Parts:

  • Bottle clamp
  • 2 Hanger screws
  • Filter
  • Small Funnel
  • Fillable water bottle


Screw in both of the hangers screws into the Bottle Clamp so the design sits flush. Then twist the hanger screws until the water bottle you would like to be filled sits concentrically in the Bottle Clamp. After the fillable bottle is secured, place the small funnel in the Bottle clamp with the end going into the fillable bottle. Finally, place your water bottle filter into the top of the bottle clamp so it sits snuggly, but does not press down too hard on the filter. (This friction could rip the coffee filter)



Step 5: Tasteless Water!



All that is left to do is to put water in the filter and try it! After testing the flowrate of the filter given different crushed carbon fineness, this filter dispensed water at 10.35ml/min. This is still relatively slow when compared to Brita filters but offers a cheap and easy way to filter water with poor taste. To increase the filtering speed, you can continuously pour water into the filter as it will slow down when there is less supply of water in the bottle. Additionally, there are many additional layers that can increase the effectiveness of the filter. Brita uses ionized particles in combination with crushed activated carbon to filter out EVEN MORE containments. While the constant use of water bottles is likely inevitable, this design offers a proof of concept for an alternative approach for filtering taste out of water. Given further improvements to my design perhaps a more convenient and effective design can be developed. Pushing us towards a direction of decreased usage and disposal of plastic water bottles.