Portable reverse osmosis water processors are sold for personal water purification in various locations. To work effectively, the water feeding to these units should be under some pressure (280 kPa (40 psi) or greater is the norm). Portable reverse osmosis water processors can be used by people who live in rural areas without clean water, far away from the city's water pipes. Rural people filter river or ocean water themselves, as the device is easy to use (saline water may need special membranes). Some travelers on long boating, fishing, or island camping trips, or in countries where the local water supply is polluted or substandard, use reverse osmosis water processors coupled with one or more ultraviolet sterilizers.
Ultraviolet light (UV) is very effective at inactivating cysts, in low turbidity water. UV light's disinfection effectiveness decreases as turbidity increases, a result of the absorption, scattering, and shadowing caused by the suspended solids. The main disadvantage to the use of UV radiation is that, like ozone treatment, it leaves no residual disinfectant in the water; therefore, it is sometimes necessary to add a residual disinfectant after the primary disinfection process. This is often done through the addition of chloramines, discussed above as a primary disinfectant. When used in this manner, chloramines provide an effective residual disinfectant with very few of the negative effects of chlorination.
Photo by F. TronchinDepending on the geographic location of the wilderness area you are visiting and the time of year, temperatures can vary dramatically over the course of 24 hours. Layer your clothing to stay warm and keep your pack light. Pack silk long johns, t-shirts, trekking pants that convert to shorts, underwear, socks, and nightclothes. A fleece jacket, windbreaker, and waterproof outer jacket should be enough to handle most conditions. Wear a good pair of hiking boots, but pack a pair of sandals and water shoes. Round out your wardrobe with gloves, hat, and a scarf.
The practice of water treatment soon became mainstream and common, and the virtues of the system were made starkly apparent after the investigations of the physician John Snow during the 1854 Broad Street cholera outbreak. Snow was sceptical of the then-dominant miasma theory that stated that diseases were caused by noxious "bad airs". Although the germ theory of disease had not yet been developed, Snow's observations led him to discount the prevailing theory. His 1855 essay On the Mode of Communication of Cholera conclusively demonstrated the role of the water supply in spreading the cholera epidemic in Soho, with the use of a dot distribution map and statistical proof to illustrate the connection between the quality of the water source and cholera cases. His data convinced the local council to disable the water pump, which promptly ended the outbreak.
Reverse osmosis per its construction removes both harmful contaminants present in the water, as well as some desirable minerals. Modern studies on this matter have been quite shallow, citing lack of funding and interest in such study, as re-mineralization on the treatment plants today is done to prevent pipeline corrosion without going into human health aspect. They do, however link to older, more thorough studies that at one hand show some relation between long-term health effects and consumption of water low on calcium and magnesium, on the other confess that none of these older studies comply to modern standards of research 
A properly packed backpack is requisite to your comfort and safety. Incorrect weight distribution leads to muscle aches and unnecessary strain on your spine. Place heavy items – water, food, and cooking gear – in the middle of your pack, close to your body. Use medium weight items – clothing, tarps, and rain gear – to cushion the heavier items, securing them, so the weight does not shift while you are hiking. Pack your sleeping bag in the bottom of your backpack or tie to the bottom. Store items that you are likely to need more frequently in the side and outer pockets – compass and map, sunglasses, toilet tissue and trowel, sunscreen, bug repellent, pocketknife, flashlight, snacks, and a small towel.
The goals of the treatment are to remove unwanted constituents in the water and to make it safe to drink or fit for a specific purpose in industry or medical applications. Widely varied techniques are available to remove contaminants like fine solids, micro-organisms and some dissolved inorganic and organic materials, or environmental persistent pharmaceutical pollutants. The choice of method will depend on the quality of the water being treated, the cost of the treatment process and the quality standards expected of the processed water.
STAT: The number of annual deaths from ESD in the U.S. are unknown, since they are counted among all drownings. But anecdotal evidence shows that ESD is widespread. ESD prevention groups have successfully urged some states to enact safety standards, including the installation of ground-fault circuit interrupters and a central shutoff for a dock's electrical system.