A reverse osmosis filter is the do-it-all of water purification. The process is the only one that addresses both harmful microorganisms and pollutants at the same time. It works by forcing water under pressure through a membrane made of thin film composite, with a inner matrix of dense polymers. The result leaves purified water on one side of the membrane, and contaminants on the other side. The technology is reliable, but expensive and relatively cumbersome, and requires electricity to work. It is therefore a sound choice for use in fixed positions or by those who can afford to tow a small trailer with a small electrical generator around, but anyone on the move or without access to electricity needs to use other methods.
As science and technology continue to improve, more efficient systems in purifying water are invented, established, and standardized. In the United States, laws are passed to ensure that businesses and corporations who manufacture and distribute water adhere to strict purification standards. Local municipalities are also held to strict standards in order to ensure that communities are given clean water consistently.
In a reverse osmosis filter system, your regular water pressure pushes the water through a membrane and additional filters to remove impurities, which are then flushed down the drain. It’s a rigorous filtering process, a GE Reverse Osmosis System filters water three times, for example. Membranes and filters need to be replaced every six months to two years depending on the type of filter and how much water you use.
If you want to take a long swim underwater, the trick is to breathe in and out a few times and take a big gulp of air before you submerge. Right? Dead wrong. Hyperventilating not only doesn't increase the oxygen in your blood, it also decreases the amount of CO2, the compound that informs the brain of the need to breathe. Without that natural signal, you may hold your breath until you pass out and drown. This is known as shallow-water blackout.
Despite its efficiency in killing microorganisms, UV radiation will not remove heavy metals and particles. Something else to consider is the high maintenance requirement for a UV purification system. Frequent cleaning and proper part replacement are necessary requirements in maintaining a properly functioning system. Read our article on UV water purification systems for home to find out more.
Within the United States Marine Corps, the reverse osmosis water purification unit has been replaced by both the Lightweight Water Purification System and Tactical Water Purification Systems. The Lightweight Water Purification Systems can be transported by Humvee and filter 470 litres (120 US gal) per hour. The Tactical Water Purification Systems can be carried on a Medium Tactical Vehicle Replacement truck, and can filter 4,500 to 5,700 litres (1,200 to 1,500 US gal) per hour.