Homemade Water Filter
The relative ease of building your own homemade water filter means that there is no reason you need to live with unhealthful water, whether it comes from your public system or from a private well. Many manufacturers sell great systems at a wide range in prices. But there are a number of reasons why you might want to build a homemade water filter instead of buying one.
It could be that the budget is very tight and the water not so clean; building a simple filter could provide enough drinking water without spending many hundreds of dollars. Or perhaps this is a science experiment for school, scouts or just for fun. The reason makes a difference and here’s why.
If this is for fun or for a student project, or to absolutely minimize costs, you’ll want to go back to basics, not using professional filtering materials. But this takes longer and results in a cruder device compared to a design that uses store-bought filters and other components. Before we provide a couple of simple homemade water filter designs, we’ll discuss how to save big on a system that uses parts that can be purchased online.
A compromise. One of the best filter systems is the Berkey water filter system; it is not the cheapest option but may be your best option. As explained elsewhere on this website, this system uses gravity flow, from an upper container through two very effective filters, into a lower container with a spigot for pouring. If you get hold of two buckets (make sure they are food-grade buckets suitable for drinking water and won’t leave a plastic taste), the spigot (available online from supply houses) and the two filters, you can build your own version of a Berkey homemade water filter system for a fraction of the price.
Now, the two filters are around $100 online from the manufacturer, eBay or other sources. The other parts should be like another $10 or so. Your cost then amounts to say $115 but that’s way less than a new Berkey system (and they sell ceramic filters for less, but the life is shorter so it depends on your expected water demand). And this will be a pretty serious homemade water filter system.
Build it from scratch. If your desire is to build a homemade water filter from scratch, there are many designs available online. A common method to build a very rudimentary homemade water filter is to take a 2-liter soft drink bottle and cut off a thin slice including the bottom, keeping the top with its opening and cap. Turn it upside down and cram sterile cotton or other, similar filtering material down near the bottom opening. Some instructions suggest you keep the plastic cap in place but drill a hole in it to allow a drinking straw to be shoved through it, and let the filtered water come through the smaller opening but that may not be the best way.
You then add a couple inches of charcoal granules atop the cotton; these can be obtained at a pet fish store as they are used in aquarium filters. Above the charcoal is a layer of fine sand, and then coarse sand. You make these an inch or two each. On top of the coarse sand goes alternating layers of smaller gravel and medium pea gravel or a bit larger.
Alternate the gravel layers until you’re near the top of the bottle, at which point you place a coffee filter as the first line of filtration; this will help the bottom layers last longer and is easily replaced. Another variation of the layering sequence is shown in the sketch to the lower right.
Once all is in place, pour some water into the filter; it must saturate all the layers so it will take awhile to come out the bottom. You can crimp the straw, if you used that, or put the bottle cap on when you’re not drawing water from your homemade water filter. If you find that you’ll not be using the filter for a period of time, it might be worth letting it dry out thoroughly. Also, poke two holes in the plastic bottle near the “top” and tie string so you can hang your filter.
Of course there are many other homemade water filter designs, some for camping/survival, some for smaller filters and some for larger systems. We like the simplified Berkey design as a compromise; not as cheap as a 100% made-from-scratch homemade water filter, but very effective and much cheaper than buying the real thing