Basic Survival Water Filter Lesson

Description of Lesson:

In this lesson students will go through the process of creating a basic water filter while learning basic filtration and water safety concepts as well as utilizing waste materials and renewable resources. This lesson is targeted for students grades six through eight and can be conducted indoors or outdoors but outdoors is recommended because the construction can be messy and if water is run through the filter it will likely make a bit of a mess.

Lesson Objectives:

• Students will gain hands-on experience with creating their own basic water filters using basic materials
• Students will be able to use the engineering design process to improve upon or alter their water filters
• Students will gain a basic comprehension of water filtration systems and purification methods

Benchmarks and Standards for Technological and Engineering Literacy

Core Disciplinary Standards

• Nature and Characteristics of Technology and Engineering: a basic understanding of how nature (understanding of the natural world) as well as chemistry and biology (engineering being an interdisciplinary subject) work are imperative when creating a water filter.
• Benchmarks: STEL-1J Develop innovative products and systems that solve problems and extend capabilities based on individual or collective needs or wants (needing potable water and creating a filter to get it).
• Integration of Knowledge, Technologies, and Practices: understanding of some basic chemistry and biology concepts are necessary to design a filter (technology and engineering are advanced by other fields).
• Benchmarks: STEL-3G Explain how knowledge gained from other content areas affects the development of technological products and systems (students explain how chemistry is used in the carbon filter).

Practices

• Attention to Ethics: students utilize materials that are considered waste and are therefore becoming more environmentally conscious.
• Making and Doing: students create the water filter by conducting a hands-on project where they have to assemble the materials using the correct methods.

Contexts

• Medical and Health Related Technologies: the water filter is designed to help people by reducing the possibility of contracting diseases or health complications from drinking non-potable water.

The materials needed for this project are meant to be items easily found either in nature or in developed areas due to the fact that, in survival situations, most people will not have access to or knowledge of how to use industrial grade water filters and even consumer grade water filters may be hard to find. These materials are very common in modern life or are easy to obtain and many of these materials can be substituted if the need arises.

The materials needed for this project are:

1. 1x Empty Water Bottle (cleaned and with no holes, can be found in almost all recycling or trash bins, free-$1)
2. 1x Matching Water Bottle Cap (that can hold a seal on the bottle, free-$1)
3. 1x Coffee Filter (can be found anywhere that would have coffee machines, can be substituted with cotton, $1-2)
4. 1x Pair of Scissors (or any other sharp tool used for cutting, $5-10)
5. 1x Piece of Cloth (clean, higher thread count is better, free-$5)
6. 1x Rubber Band (can be found almost anywhere with office supplies, can be substituted with any other elastic band or with a string tied around the filter tightly, $1-2)
7. ~4 cups of Sand (rough estimate, can be found on creek beds or riverbanks, $5-10)
8. ~4 cups of Charcoal Powder (rough estimate, can be found in burnt-out campfires or from grills and other similar cooking tools, can be made by burning wood, be careful of possible chemicals in fire starters and other similar fire lighters used in things like grilling, $5-10)

There are other things needed for completing the process of actually purifying the water such as the water that needs to be filtered, a clean container to hold the filtered water and either chemicals or a heat source to purify the filtered water but this lesson will focus solely on the filter itself.

• Students will start out the process of building the filter by putting a small hole in the cap of the water bottle using the scissors.
• This can be done by poking the sharp point of the scissors into the middle of the cap and twisting the scissors until it pokes through.
• This hole will serve as the stopgap for the water flowing through and prevents the filter materials from falling out the bottom.
• If the cap has not been cleaned before starting the project, it should be done before progressing any further as it will affect the cleanliness of the water.

• Students will then create the input for the water filter by cutting off roughly 1/2-3/4 inch off the bottom of the bottle as pictured.
• If the bottle has not been cleaned yet, now would be a good time to clean it.
• The opening on the bottom of the bottle will be where we will be inserting the rest of the components for the filter as well as providing the opening for which the non-potable water will flow into.
• Once this step is complete the cap should be reattached snugly.

• Students will next take the coffee filter and cut the top third off so that it will fit in the bottle easier and then take the extra material and put it inside the resulting filter "cup" as shown above to provide more layers of filtering. This will act as both the support for the non-solid components of the filter as well as acting as the last mechanical filter that the water will pass through.

• Students will carefully break down any large chunks of charcoal for the carbon filter.
• The reason for this is that the more the charcoal is broken down, the more surface area is exposed and thus the more chemicals it can absorb from the water and on top of that the powdered charcoal is easier to add to the filter.

• Students will add charcoal dust until it is roughly the same height of the coffee filter.
• The coffee filter will not be a perfect circle so do not worry if some charcoal gets behind or underneath it.
• The reason for this step is to add a carbon filter layer that will remove mercury, lead, and chlorine from the water.

• Students will then separate the remaining space in the bottle into thirds and fill the bottom third with sand, the middle third with charcoal powder, and the top third with sand again (if needed, expand images to see all three stages).
• The point of adding these alternating layers is to catch anything that the previous layers may have missed and to increase the exposure of the materials to the water.
• The sand layers act as mechanical filters that remove any large particles in the water and, as stated before, the charcoal layers act as a carbon filters.

• Students will lastly take the cloth and lay it over the top of the filter and then use the rubber band to secure it to the filter.
• The reason for this is that the cloth will act as a mechanical filter that will keep really large particles like dirt out of the filter as well as keeping the non-solid parts of the filter in the bottle.
• The rubber band keeps the fabric from becoming loose or falling off.

• Students will test their filters by slowly running water through them in a sink.
• This process will likely be messy so its best to keep the filters in the sink until they dry or stop draining.
• The filters will need some water running through them for a while before they are usable because the filter layers need to settle inside the bottle and the charcoal that got stuck beneath the coffee filter needs to be washed out.
• This basic filter is fairly slow so you may have to be patient in waiting for water to traverse the whole thing.
• Important: The water coming out of the filter is NOT potable automatically, it needs further treatment via chemicals like chlorine or heat treatment such as boiling to remove any remaining harmful microorganisms. This can be done at home under parental supervision.
• Students will then go home and make another basic filter using the same steps but utilizing alternate materials and will compare results such as water clarity and filter speed.