Building an Off Grid Water Filtration System

Living off grid often means being a resourceful DIY’er, and cutting ties with the grid means removing yourself from city water. Whether your water source comes from rainwater collection, stream, pond, or well, you’ll definitely need a way to make sure the water you have on hand is safe to drink. For that, you’ll need to invest in a decent water filtration system.

What do you need for off grid water filtration? Off grid water filtration requires several phases, which include: screening, two or more in-line filters of increasing fineness, a carbon filter, and a UV light.

The process starts at the initial water intake, with a screening mechanism that keeps out the largest particles (leaves, sand, dirt, etc). It then needs to pass through several filters starting with a 50 micron filter, then a 20 or 10 micron filter, before going to a 10 or 5 micron filter. These filters alone will not kill or remove bacteria from the water, so the water will then need to be disinfected. The most common disinfectant used (particularly by on grid water sources) is clorinization, however many people opt for ultraviolet disinfection rather than adding any chemical to their drinking water.

How Does Water Filtration Work?

Most people don’t put a whole lot of thought into their drinking water. They are used to simply turning on a faucet, or just cracking open a fresh bottle, but most people do not live off grid. We have to put a little thought and planning into insuring a safe drinking source.

Water purification doesn’t happen in one step, but rather several steps. There are many different sized contaminants in any given water source. If you ran water through only one filter, it would quickly become clogged and unusable. The first step takes out the larger particles in the water, the second takes out smaller contaminants, the third, even smaller contaminants, and the last step kills any bacteria that is left.

Water filters are rated in microns. A micron is a unit of measure equal to one millionth of a meter. This measurement is what you will need to choose your filters, and decide where they will go in your filtration system.

The filtration process is done by “stacking” various filters starting with the largest opening (highest micron rating), and ending with the smallest opening (lowest micron rating).

From your water source, you may want to start with something like a 300 micron mesh filter. This filter will keep out leaves, pebbles, bugs, and basically any contaminant that is visible by the naked eye.

After the water passes through the 300 micron (largest opening filter), it then passes through the next smallest opening filter, which could be something like a 50 micron filter. This will help remove any left over bits of sand or dirt. After that it can move down to a 20 or 10 micron filter, and then a 10, 5, or even a 1 micron filter.

From there, water can be refined even further by microfiltration (.03 microns), ultrafiltration (.002-.1 microns), nanofiltration or reverse osmosis (.001 microns). These filtration systems remove all minerals from the water, as well as many viruses and bacteria, however they tend to be more expensive, and generally, a rating of 1-5 microns is all that is needed, especially in a system that includes the next type of filter.

Ultra Violet filters expose water to UV light, killing any leftover bacteria and viruses. These filters are usually one of the last steps of the filtration system, and insure there is nothing in the water that can make you sick.

The addition of a carbon filter can improve the taste and smell of water.

Water filtration is probably one area you don’t want to DYI without being very well informed, or even consulting a professional. There are thousands of filtration products on the market, and its best to get some knowledgeable tips about which products are credible and effective, but having a little background in how it works beforehand will give you a leg up.

It’s also noteworthy to mention that after you have your filtration system installed, you may want to have the water tested to insure that it is working as it should. You will also need to schedule cleaning or replacing the filters based on the manufacturers recommendations.

Dangers of Inadequately Filtered Water

Water is of course one of the most important resources you need to survive. Whether you get your water from a tap, or from some other source, many harmful substances could be unknowingly lurking in the water.

Tap Water commonly contains additives such as chloramines, and fluoride, but can also include other harmful matter such as petrochemicals, lead, pesticides, or pharmaceuticals. Tap water can also become contaminated if there is any damage to pipes anywhere in the system. Although this traditional source of water is generally considered safe to drink, extra filtration of some kind may not be a bad idea.

Bottled or jugged water you may think to be specifically pure, but that’s not necessarily the case either. Bottled water is not subject to any additional regulation than tap water, in fact, some of it is actually just packaged tap water anyway. Worse yet, there has been as many as 38 contaminates found in the 10 popular brands, including disinfection byproducts, industrial chemicals, arsenic, fertilizer residue, and pain medication. That will make you think again, huh?

While you can add additional filtration to tap water, Off grid water systems have to go a few steps further, as they these systems are often beginning with “dirty” water, rather than filtering water that has already been through previous filtering, and treated with disinfectants.

As discussed above, off grid systems have to deal with bigger debris first, such as dirt, silt, clay partials, minerals and metals. These aren’t necessarily harmful to consume, but they don’t taste too great, and can have other harmful effects. Iron and manganese in water can cause stains in clothing when washed, or even discolor porcelain and other dishes. Mineral-rich water will also build up in your pipes overtime, reducing water pressure, and creating a lot of headaches down the road.

The biggest concern to water filtration is the removal of pathogens such as harmful bacteria and parasites. A microscopic parasite called Giardia Intenstinalis can cause an illness called Giariasis which will cause diarrhea that could last as long as six weeks. Another parasite that causes similar symptoms is cryptosporidium, and this nasty guy is even resistant to chlorine.

This is just scratching the service of the harmful organisms that might be found in untreated water, to add on top of the other things that can also show up in tap and bottled water. Needless to say, its important to spend a little extra time with this if you are designing a DYI system.