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Wednesday, June 27, 2018

Viruses, Parasites, Bacteria, and Micron Filter Purifiers

Water Filtration and-or Purifiers Reference

Water purification methods

  1. 1. WATER PURIFICATION METHODS Natural purification Purification at small scale Purification at large scale
  1. 2.Natural purification methods •Aeration •Oxidation •Filtration through layers of soil
    •Aquatic animals
    •Flow of water
    • Pre filter
    • Activated carbon
    • Ultra violet chamber
    • Electronic monitoring system
  1. 9. 2. BOILING
    • Advantages: – Simple and effective method of purification – Will kill many waterborne bacteria through the intense heat – Uses local available materials. 
    • Disadvantages: – Can sometimes be difficult, time consuming, and cost inefficient because of the high volume of fuel used – Will not remove mud from ‘murky’ water – Will not remove suspended or dissolved compounds
  1. 11.
    Advantages: – Easy to use method of chemical purification of water – Effective at killing bacteria and viruses – Inexpensive. 
    Disadvantages: – Not effective at killing all parasites. – Complex compounds can form with organic material which over time can be hazardous to health. – It is best to use the water in a shorter period of time and store it in a plastic container in a cool and shaded place.
    • Halazone tablet is available in the market.
    • Good to disinfect the small quantities of water.
    • Costly.
    • 0.5 g sufficient to disinfect 20 liter of water.
  1. 15. ALUM
  1. 16. IODINE
    • Emergency method to disinfect the water.
    • Two drops of iodine with 2% ethanol solution sufficient for I liter of water.
    • Larger amount will stimulate thyroid activity.
    • No longer recommended for disinfection of water.
    • It will alter the color, smell and taste of water.

This article is part of our series: Hydration Basics.
 A hiker refills her water bottle from a lake using a squeeze filter

Water treatment is important to maintaining your health in the outdoors. Not all water sources are unsafe, but even the most pristine-looking source can make you sick. If livestock, wildlife or humans can reach an area, so can contaminants transmitted via their fecal matter.
As more and more of us explore wild places, contamination levels rise. Why play intestinal roulette when you have so many options for treating your water?

This article offers guidance on selecting a water-treatment method to use in the outdoors. To learn about options for travel abroad, read Water Treatment for International Travel.
Consider these factors when choosing a water filter or other water-treatment method:
  • Filters vs. purifiers: Know what you’re trying to avoid and the basic methods for avoiding it.
  • Types of water filters and water purifiers: The effort required for each type of water-treatment method varies, as does the time for water to be ready to drink.
  • The role of a prefilter: If you have to treat water from a murky source, it’s a valuable accessory to have.
  • Know water treatment best practices: Even the best filter or purifier isn’t effective if you don’t follow some basic hygiene and usage guidelines.

Water Filters vs. Water Purifiers

The difference between a water filter and a water purifier is the size of the microorganism each combats:

Water filters work by physically straining out protozoan cysts (such as Cryptosporidium and Giardia lamblia) and bacteria (such as E. coli, Salmonella, Campylobacter and Shigella). These biological pathogens are the main water concerns if you’re traveling in the U.S. and Canada.

Water purifiers also combat viruses, which are too tiny for most filters to effectively catch. If you’re traveling in less-developed areas of the world, consider products that also provide protection for viruses (such as hepatitis A, rotavirus and norovirus).

How Water Filters and Purifiers Work

Every filter and many purifiers include an internal element or cartridge, a component that has microscopic pores that catch debris, protozoa and bacteria. Over time, strained matter gums up an element’s pores, requiring it to be cleaned and eventually replaced.

Most purifiers use chemicals (such as iodine) to kill viruses, which are too small for most filter elements. Another purification method relies instead on ultraviolet light to treat the pathogens.

Many filters and purifiers also include activated carbon in their elements because it’s effective at removing unpleasant tastes from things like leaf tannins. Activated carbon also reduces contaminants like pesticides and other industrial chemicals.

The Role of a Prefilter

Different factors can murk up your water in different ways, such as glacial sediment, silty water, leaf debris and mud stirred up by a rainstorm. Natural particles, though not a health concern, impact how easy water is to treat, how much field maintenance is required and the lifespan of filter elements.

One way to deal with these issues is to use a prefilter. A prefilter is an accessory that simply removes large particles from your water to improve the treatment process.
Many pump-style products come with a prefliter, or you may need to purchase one separately. Here are some reasons to consider using one:
  • It helps maintain a pump filter’s flow rate, lessen cleaning chores and extend its element life.
  • It improves the effectiveness of chemical treatments.
  • It’s absolutely essential prior to using a UV purifier on nonclear water.

Types of Water Filters and Water Purifiers

Quick Reference Guide to Water Filters and Purifiers123123123
Method All-around performance Large volume Low maintenance Ease of use Low weight Low cost Speed
Pump filters and purifiers x x

Gravity filters and purifiers

Ultraviolet (UV) purifiers

x x

Bottle filters and purifiers

x x
Squeeze filters

x x
Straw-style filters

x x

 x x x x
Boiling x  x  x

The summary below covers the basics for each treatment method, but innovation has produced hybrid designs and many unique products. So use this assessment as a starting point, then delve deeply into product descriptions, specs and reviews.

Pump Filters and Purifiers

A hiker refills his water bottle from a stream using a pump filter

Drop the intake hose into your source and the outlet hose into your water bottle, then work the pump. Some models thread directly to a bottle or reservoir. Pump mechanisms differ, as do flow rates, so compare specs.

  • You can process precisely the amount of water you need.
  • Water can be pulled from seeps and shallow water sources.
  • The internal element or cartridge is replaceable.
  • Pumping can be a chore, especially at the end of the element’s lifespan.
  • Field cleaning of the element is required.
  • Weight and bulk are greater than other treatment methods.

Gravity Filters and Purifiers

A camper hangs a gravity filter from a treeFill a reservoir, find a suitable place to hang everything up and wait. Most models come with a pair of reservoirs and an inline filter, though the exact setup and provided water containers can vary.

  • Gravity does the work for you.
  • You can easily process large quantities of water for a big group.
  • The element or cartridge is replaceable.
  • It can be hard to find a place to hang reservoirs.
  • Treatment process is slower than pumping.
  • Seeps and shallow water sources can make it challenging to fill a reservoir.
  • Field cleaning of the element is required.

Ultraviolet (UV) Light Purifiers

Using an ultraviolet light purifier to sterilize water in a bottleGrab one of these pen-style devices, push a button and stir. Stop when its UV light turns off (60 seconds or so) and you will have treated all the water inside a bottle.

  • Treatment is easy and water is quickly drinkable.
  • No element cleaning and replacement are ever needed.
  • Requires batteries.
  • Silty or cloudy water impairs effectiveness, requiring you to prefilter.
  • Multiple treatments are required to produce large quantities.

Bottle Filters and Purifiers

Using a fill and sip bottle with built in filter

Offering fill-and-sip simplicity, these bottles have built-in filtration or purification elements. Some use the suction provided when you sip from a bite valve, while others work like a coffee press. Another model uses UV light.
  • Treatment is easy and water is quickly drinkable.
  • The element or cartridge is replaceable.
  • On average, lighter and cost less than pump and gravity filters.
  • Water quantity is limited by bottle size.
  • Field cleaning of the element is required.

Squeeze Filters

Using a squeeze bottle with built in filter

This broad category is similar to bottle filters except that you’re filling a small reservoir, then squeezing water through the filtration element.
  • Treatment is easy and water is quickly drinkable.
  • The element or cartridge is replaceable.
  • Some double as a gravity filter or straw-style filter.
  • On average, lighter, smaller and cost less than pump and gravity filters.
  • Water quantity is limited by reservoir, flask or bottle size.
  • Field cleaning of the element is required.

Straw-Style Filters

Using a straw filter from a stream

Providing water on demand, these cylinders have a built-in element that lets you slurp directly from the source.
  • Treatment is easy and water is quickly drinkable.
  • On average, lighter and cost less than pump and gravity filters.
  • Water is only available when you’re at a water source.
  • Generally only a 1-person treatment option.
  • Field cleaning of the element is required.
  • Not all models have replaceable elements.


Two bottles of water neutralizing tabletsEffective against protozoa, bacteria and viruses, you simply add them to gathered water and wait. Products are typically iodine- or chlorine-based and available in drops, pills or gadgets that mix base ingredients.

  • Easy to use.
  • Ultra-inexpensive, ultra-small and ultralight.
  • An excellent backup method to pack in case your main filter breaks.
  • Wait time before drinking is 30 minutes to 4 hours, longer for icy cold water.
  • Iodine products impart a chemical taste—can be countered by taste-neutralizer tablets.
  • Iodine products aren’t effective against Cryptosporidium, though they work fine against other types of protozoa.
  • Iodine products can be a concern to pregnant women and people with a thyroid condition.


A backpacker boils water

Your stove, fuel and a pot are an effective treatment system to combat the full spectrum of biological pathogens. Bring water to a rolling boil for 1 minute; if you’re above 6,500 feet, boil it for 3 minutes.
  • The only additional supply you need to pack along is extra fuel.
  • Murky water doesn’t impair effectiveness.
  • Serves as a readily available backup method in case your main filter breaks.
  • Time and effort required to bring water to a boil.
  • Wait time for the water to cool.
  • If it’s your primary treatment method, you need to pack an extra fuel container.

Water Treatment Tips and Best Practices

Avoiding a few key mistakes and taking a few precautions will make any treatment method more effective.
  • Separate and clearly designate dirty and clean water containers.
  • Pay close attention to directions because every product has detailed steps to avoid cross contamination (introducing nontreated water into your treated water).
  • Seek out clean water because sediment impairs treatment effectiveness. If only murky sources are available, use a prefilter or allow sediment to settle from gathered water.
  • Keep your hands clean by packing hand sanitizer and using it often.
  • Keep camp, toilet and dishwashing areas at least 200 feet from any water source. For details on all Leave No Trace principles see

    Bacteria & Virus Issues

    Microbial and organic contaminants can't always be detected through sight, smell or taste. You might go years before realizing a problem exists. 

    Although some waterborne microbes can cause illness, many microbes are harmless or even beneficial. Very small levels of microbes are naturally present in many water supplies, but some are more dangerous than others. Some of the more dangerous microbial contaminants, such as E. coli, Giardia, and Cryptosporidium, can cause gastrointestinal problems and flu-like symptoms commonly attributed to undercooked or improperly stored food. They include:

    Bacteria: Single-celled organisms lacking well-defined nuclear membranes and other specialized functional cell parts which reproduce by cell division or spores. Bacteria may be free-living organisms or parasites. Bacteria (along with fungi) are decomposers that break down the wastes and bodies of dead organisms, making their components available for reuse. Bacterial cells range from about 1 to 10 microns in length and from 0.2 to 1 micron in width. They exist almost everywhere on earth. Some bacteria are helpful to humans, while others are harmful.

    Viruses:  Parasitic infectious microbes, composed almost entirely of protein and nucleic acids, which can cause disease(s) in humans. Viruses can reproduce only within living cells. They are 0.004 to 0.1 microns in size, which is about 100 times smaller than bacteria.

    Cysts: Capsules or protective sacs produced by many protozoans (as well as some bacteria and algae) as preparation for entering a resting or a specialized reproductive stage. Similar to spores, cysts tend to be more resistant to destruction by disinfection. Fortunately, protozoan cysts are typically 2 to 50 microns in diameter and can be removed from water by fine filtration.

    There are both chemical and physical ways to disinfect water. Chemical disinfection often uses halogens such as chlorine, iodine, bromine, or ozone, while common physical choices are ultraviolet (UV) light, ultrafiltration, and distillation. These processes can eliminate 99.9 - 99.9999% of harmful microorganisms.
    Water treatment can address pathogenic microbiologicals through the following techniques:


    The treatment process in which chlorine gas or a chlorine solution is added to water for disinfection and control of microorganisms. Chlorination is also used in the oxidation of dissolved iron, manganese, and hydrogen sulfide impurities. This method of disinfection involves adding chlorine to water to make it safer to drink. It’s common, cost-effective, and quick, killing many pathogenic microorganisms. It can even oxidize or break down iron, manganese, and hydrogen sulfide, which can result in water that is clearer and tastes better.
    Some people find that chlorine gives water its own objectionable chemical taste and odor. It also can produce disinfection byproducts (which may cause health issues) by reacting with other substances in water when stored. These byproducts can often be filtered out with activated carbon.

    Ultraviolet (UV) Light

    The UV disinfection method, which does not involve chemicals, has long been popular for commercial use, but is becoming more common in homes. UV systems expose water to light at just the right wavelength for killing microbes. It’s a way to kill bacteria, viruses, fungi, protozoans, and cysts that may be present in the water. 

    The effectiveness of UV treatment depends on the strength and intensity of the light, the amount of time the light shines through the water, and the quantity of particles present in the water. The light source must be kept clean and the UV lamp replaced periodically. UV light treatment can’t remove gases, heavy metals, and particulates; for that reason higher-end systems may include additional filtration such as activated carbon.


    Ozone is produced when oxygen is exposed to high-voltage current. The use of ozone in water treatment can destroy viruses, bacteria, and other microorganisms, while also removing iron, sulfur and manganese. Ozone does its job quickly and then rapidly decomposes, cutting down on the introduction of harmful disinfection byproducts and foul tastes or odors associated with chlorination. This process tends to be more costly and energy-consuming and is typically used commercially or by large municipalities.

    Click here to find a water treatment provider who can help with bacteria and virus issues.