How to Filter Your Own Drinking Water

My wife Emma and I have been looking for property in Central America for over a year now. During the search, we have been volunteering on different spots, learning from those who have already been there and done that, as well as experimenting with ideas we have for our own future farm. One of the things that is always on our minds is water.

Drinking Water (Courtesy of Jose Jaf)
Drinking Water (Courtesy of Jose Jaf)

Of course, aiming to be as self-sufficient as possible, we hope to harvest our own water. We’ll have ground-level water catchments, such as contour swales, keyline dams, and rain gardens. Our rooftop runoff is a source of constant brainstorming, our hope to have a series of tanks—yes—but also a thoughtful overflow system to take advantage of the tropical storms without suffering from them. (No floods, no mudslides!) From the tanks, we’ll provide our kitchen sink, laundry basin, shower and bathroom sink with freshwater. Then, ultimately, the greywater from these drains will be sent into a greywater filtering design to once more contribute to the landscape. (Toilets will be dry composting)

We are also planning a water filtering system to provide us with drinking water. In Central America, a land infamous for parasites and stomach bugs, safe drinking water is a major concern, and it can make a huge difference as to whether we’ll have the energy and hydration necessary for tackling the construction of all those other watery dreams. In short, it’s much more than simply quenching our thirst. Of course, neither we nor Central America are alone in this, as this year has had more than one incident of widespread water-borne illnesses coming from municipal water sources. Luckily, we think we have our situation under control.

Eco-Filtro

Our initial (and probably still first choice) plan for filtering water is using a set-up common in Guatemala: Eco-Filtro. Eco-Filtro started out as an NGO, hoping to get potable water to over a million rural families by 2020. The NGO later transitioned into being a social business, using “business practices to achieve its social objective”. Nowadays, they have much more going on: Walk around Antigua (Guatemala), and on nearly every block, at some storefront, pedestrians will have free, fresh drinking water at their disposal, so no one needs to buy bottled water.

Free Drinking Water
Free Drinking Water

The filtration system is actually a locally produced design. It was based on an award-winning model by a Guatemalan biochemist, Jose Fernanado Mazariegos Anleu. The filter is created using three, abundant natural resources: clay, sawdust, and colloidal sliver. The clay creates micro channels that catch solid contaminants, bacteria and parasites. The sawdust is used to make activated carbon, which removes bad smells, funny tastes and cloudiness. Lastly, the colloidal silver (a controversial thing that, from personal experience, we happen to think works) provides a little extra insurance for taking on bacteria.

Ideally, we would have access to these filters, which can produce one to two liters of drinking water per hour, a process which simply requires pouring water into the filter at the top of container and getting it from a spigot at the bottom. Properly maintained filters (they must be sponged clean with filtered water every three months) last for two years and are replaced for about 25 USD. Finally, the old filters make fantastic plant pots, something we first learned at Earth Lodge, an eco-hotel where we often volunteer.

UV Water Purification

While Earth Lodge has a collection of five eco-filters working to keep the drinking water supply for the hotel, the policy there is also to be extra careful with any can fresh fruit or vegetables that are being rinsed. For years now, the kitchen staff adds a natural anti-bacterial rinse, a mixture that utilizes citrus’s cleaning power. But, the hotel has recently added a UV water purification system so that the kitchen sink—all plates, cups, flatware, produce, etc.—uses water that technically could be drunk.

UV Light (Courtesy of Richard Lewis)
UV Light (Courtesy of Richard Lewis)

The system is quite simple and uses a UV light bulb encase in a tube, which can provide on demand water. Unlike the Eco Filtro set up, which must be filled daily (often multiple times), cleaned four times a year, and so on, the UV system only requires changing a light bulb every year or so. It destroys a trustworthy 99.99% of microorganisms, needs no chemicals and requires very little electricity, easily covered by solar power (or whatever renewable source). It doesn’t affect taste or smell as chlorine (also not exactly healthy) and other chemicals do.

There are some downsides to UV water purification, but most of them are easily addressed. Obviously, it does call for power to function, which, in some situations, as with our off-grid aspirations, could be a serious consideration. UV also doesn’t do anything to filter out solids or substances (petroleum, chlorine, salts or heavy metals) in the water, and it doesn’t work with murky water. In other words, for rainwater, it’ll likely be fine; otherwise, it may only really get the job done in conjunction with another, though very basic, filtering system.

DIY Water Filter

UV may be consideration at some point. Eco Filtro systems are great, but the problem we’ve run into is that they aren’t available everywhere. So, we’ve also prepared ourselves to make our own simple yet effective filtering assembly should the case be that an Eco-Filtro is not available. Of course, we are not innovators in this (NGOs are helping get potable water all over the world), which means the following is a scientifically verified method (not merely our idea) and easily accomplished, even for two novices like us.

As for materials and tools, the list is short. You’ll need two food-grade plastic buckets (other containers are possible, but these are often available for free from restaurants) with lids, a food-grade water spout (available online for a few dollars), and minor plumbing fittings to connect the buckets (including an O-ring and screen). The filtering part will be a combination of gravel for bigger solids, sand for other particulars, and activated charcoal for micro stuff. Activated charcoal is available in most pest shops, but some say that normal wood charcoal will also work just fine. The only tool that may not be around would be a drill with a hole saw (suited for the plumbing fittings and one for the spigot), but a knife and hacksaw can work.

To make the system, first, put one bucket atop the other, the bottom having its lid on. Then, drill a hole through the bottom of the top and the lid of the bottom. Connect the holes with the plumbing fixtures, with all connection obviously being watertight. Next, install the spigot around the bottom lip of the bottom bucket. Lastly, it’ll be building the filter. Cover the plumbing between the buckets with a piece of screen and O-ring, then splitting the top bucket roughly into fourths, fill one quarter with activated charcoal then sand then gravel, leaving the last quarter for water. Like with any good permaculture water system, gravity will do the work.

Most permaculturalists I know aren’t extremely fearful of a little dirt, but in case anyone isn’t fully convinced with this DIY filter system for themselves, the water can be further purified by placing it a glass container in the sun for a few hours or boiling it. But, by the overwhelming majority of accounts, this isn’t necessary. The more relevant idea for us is that no chemicals are required, as would happen with municipal water systems, and we can get safe drinking water from our own collection tanks.

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