FILTRATION VS PURIFICATION - WHAT YOU NEED TO KNOW

THE DIFFERENCE BETWEEN WATER FILTERS AND WATER PURIFIERS

If you’re cleaning water in the wild, you may have come across filtration or purification before. Simply put, both of these are methods that you can use to help treat your water in the wild, helping to remove harmful microorganisms that may be hiding in outdoor creeks, rivers, streams, lakes or other outdoor water sources. The main difference between the two is the level of protection they each offer. 

WHAT IS WATER FILTRATION?

Filtration is the process when solid particles in a liquid or fluid are removed by the use of a filter. It’s a process designed to remove waterborne bacteria and parasites from water, but not viruses. Filters typically have 1000s of tiny microscopic tubes, designed to let clean water pass through the filter, while stopping the larger particles (including bacteria, parasites, dirt, etc).

These types of water filters come in many shapes and sizes, including straw/in-line filters and bottle filters just to name a few. While these tubes are microscopic in size, these are usually limited to 0.1 microns. This is more than capable to catch and remove bacteria and protozoa, although the issue is when we start to look at viruses. Many viruses are smaller than 0.1 microns, so not all filtration systems can remove them.

 

 

WHAT IS WATER PURIFICATION?

Purification is the process of removing unwanted contaminants from water, including viruses. Tackling viruses has been considered much tougher, especially in filtration systems. On the microscopic scale, viruses are far smaller than bacteria and parasites, making it that much harder for backpacking filters to stop, so purification has its place to purify leftover contaminants after filtration. Purification methods comes in many forms, such as chemical treatment, UV light, physical purification or even boiling. These methods usually kill 100% of bacteria, parasites and viruses, making water completely safe.

While you may think getting a water purification system may be perfect for you, a purifier isn’t always necessary for outdoor trips. Let’s explore why.

WHEN SHOULD I FILTER WATER?

Although purifiers provide a better defence against all microorganisms than water filters, they are sometimes a bit much, depending on the trip you’re planning.

When you’re in the backcountry or the mountainside, using a filter is more than sufficient protection. It’s here in these immaculate landscapes, where human and agricultural contamination is very limited, that some of the purest water flows. The main contaminants you’ll find here will be bacteria (Salmonella and E.coli) and parasites (Protozoa, Giardia, Cryptosporidium). Contaminants like these are transferred mainly via animal or human faeces, and can be filtered out with a good filter.

Viruses, on the other hand, tend to be species-specific. This means that humans are more harmed by the spread of viruses by other humans, typically through faecal matter, than that of other animals. Viruses are more commonly found in water where the human population is closer to the water supplies you’re filtering from, and where the risk of human contamination is greater. 

Be sure to check that your water filter is made to handle outdoor water sources, down to 0.1 microns. Various filtration systems don’t filter to this microscopic size, therefore not providing sufficient protection to filter out all the bacteria and parasites.

WHEN SHOULD I PURIFY WATER?

Purification can be a great method to stay safe on the trail, since it kills viruses and often does this all in one step. This is much more essential when traveling to underdeveloped countries, where water treatment infrastructure is poor. Here the risk of human contamination without treatment of water is much greater, and purifying your water would be the safest option. You may also choose to purify your water from your local water source too, if you believe it to be too unhygienic.

It would be good practice to purify your water if you note any of the following:

• The quality of the water is lacking
• Colouration in the water
• Stagnant/non-flowing water
• Animal corpses near water
• People not practicing good hygiene near a water source

Common waterborne viruses in water sources include Hepatitis A and Norovirus. Both of these viruses can spread through human faeces where poor sanitation and contamination occur.

If you own a portable water filter, you can easily deal with viruses by first filtering your water into a pot or bottle, then boiling the water afterwards. If you’re taking this approach, be sure to keep the water boiling for at least 60 seconds, as this will kill any remaining viruses. Alternatively, after you filter your water, you can use chemical tablets, making the water completely safe from viruses. 

Some people aren’t such a fan of the chemical taste using this second approach, but it can be a quick way to make the water safe and drinkable, without the need to boil.

Using purification tablets alone won’t be enough to remove particulates like dirt, sand or other sediment, so filtering water first can help remove these larger particulates. One point to note in relation to chemical and UV light purification is that larger particulates can reduce the effectiveness of purification.

This is why filtering first can help extend the lifespan of other purification methods, and offer a big advantage if you're planning to be outdoors for longer.

CONSIDER THREE SCENARIOS:

Here are a few examples you may consider, to help determine when to use one form of treatment, or the other.

HIKING THROUGH THE WELSH BRECON BEACONS NATIONAL PARK:

You’ll filter water from fast flowing, crystal clear running streams along uncommon hiking trails. Waterborne risks in water will come from wild animals and human contamination, but along this route the risk is minimal. Since bacteria and protozoa are the main threats, and because the risk of viruses here is low, the water could be filtered easily, while removing dirt and other sediment.

Winner: Water filtration | Although if you believe there may be viruses present, you may like to purify the water additionally.

WILD CAMPING ON A LOWLAND LAKE WITH HUMANS AND WILDLIFE NEARBY:

You’ll filter water from the freshwater lake, with much wildlife and various other campers scattered nearby. The stagnant water source, although a freshwater source, increases the risk of viruses and contamination due to less natural filtration, while human contamination also increases this risk.

Winner: Purification | Filtration + purification or a physical purification device.

LOCAL B&B IN NEPAL, READY TO HIKE THE ANNAPURNA CIRCUIT:

At your local stay, you’re advised against drinking the tap water, due to pathogens from humans and animals being present. Bacteria, Parasites and Viruses may be present in water.

Winner: Purification | No need to filter, unless the water contains floating particulates.