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Portable water filtration is useful for many activities, including camping, hiking, and backpacking. It is also commonly used by military personnel and for disaster relief operations. There are several types of portable water filtration, which vary in what material is used to filter and which contaminants they are able to filter out. When choosing a portable water filter, it is important to know which contaminants may be present in the water that will be cleaned.
A simple type of water filter uses granular activated carbon as the filter material. Granular activated carbon is a form of carbon that has been processed to have a very high surface area. This enables it to absorb a large amount of contaminants. Activated carbon filters can remove organic chemicals and chlorine, and may improve the taste and smell of water. They do not, however, remove bacteria and viruses, so another treatment method is often used in conjunction with granular activated carbon.
Many portable water filtration devices utilize ceramic filters. These may come in different pore sizes — the pore size is the size of the holes in the filter, and indicates the smallest size particle that can be filtered out with that particular material. Most ceramic filters have a pore size of 0.2 to 0.3 micrometers (μm), but some have pore sizes as small as 0.01 μm. The average-sized ceramic filter can only filter out bacteria, but the filters with smaller pore sizes can filter out most viruses as well.
Reverse osmosis filters draw water through a very fine filter material. Since the pore size of the filter is very small, this can remove most impurities from water. Unfortunately, the reverse osmosis process can also waste a lot of water and is slower than most other types of filtration.
Portable water filtration devices can operate in a few different ways. Some are operated by pumps, which the user employs manually to direct water through the filter, in order to purify it. There are also water bottles that come with filtration devices built into the lids, or filter straws that can be inserted into the water bottle.
Although not technically filtration, a few other methods are also used to purify water where clean drinking water is not available. Chemicals, such as iodine, have been used by backwoods campers for many years, but they often leave an odd taste in the water. Portable ultraviolet (UV) devices are also available to disinfect water, although they remove only biological contaminants, like bacteria, and are not effective on chemicals. Similar to UV disinfection, solar water disinfection (SODIS) uses UV-rays from sunlight to purify water.