The first documented use of sand filters to purify the water supply dates to 1804, when the owner of a bleachery in Paisley, Scotland, John Gibb, installed an experimental filter, selling his unwanted surplus to the public.[37] This method was refined in the following two decades by engineers working for private water companies, and it culminated in the first treated public water supply in the world, installed by engineer James Simpson for the Chelsea Waterworks Company in London in 1829.[38] This installation provided filtered water for every resident of the area, and the network design was widely copied throughout the United Kingdom in the ensuing decades.
Strain the water. For water that’s contaminated with large particles like pebbles, insects, plant matter, or dirt, you can strain out the contaminants.[1] Line a fine-mesh strainer with muslin, cheesecloth, a clean dish towel, or even a clean cotton shirt. Place the strainer over a bowl, and pour the water through the strainer to remove the particles.

The booster pump included with this tankless reverse osmosis system requires electricity but helps to maximize the efficiency of the system. It can achieve up to a 1:1 ratio of purified to wastewater. However, in real-world use, some people found that wastewater was more like 2 gallons for every 1 gallon of purified water produced. iSprings points out that many factors affect this efficiency rating, so some variance in results is to be expected.

That brings us to filtration by manufactured filters. These devices allow us to go into microfiltration and ultrafiltration. By simply running the water through these porous ceramic filters we can effectively remove bacteria and viruses depending on the quality of the filter and the pore size. See chart above. This is where high quality filters such as the Katadyn Combi Filter can filter down to 0.2-micron level capturing Giardia, Crypto, bacteria and most viruses. Some filters are chemically impregnated to ensure complete removal of bacteria. The information below will give more detail.

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.
In the production of bottled mineral water, the water passes through a reverse osmosis water processor to remove pollutants and microorganisms. In European countries, though, such processing of natural mineral water (as defined by a European directive[10]) is not allowed under European law. In practice, a fraction of the living bacteria can and do pass through reverse osmosis membranes through minor imperfections, or bypass the membrane entirely through tiny leaks in surrounding seals. Thus, complete reverse osmosis systems may include additional water treatment stages that use ultraviolet light or ozone to prevent microbiological contamination.

Bromine and iodine can also be used as disinfectants. However, chlorine in water is over three times more effective as a disinfectant against Escherichia coli than an equivalent concentration of bromine, and over six times more effective than an equivalent concentration of iodine.[16] Iodine is commonly used for portable water purification, and bromine is common as a swimming pool disinfectant.
While nearly everyone loves the taste from this water filtration system, a few people tested the pH and complained that it wasn’t as alkaline as they hoped for in a system that adds back beneficial minerals. However, the company points out that the pH filter will raise acidity by 1-1.5 levels, so the final pH will depend on the chemistry of the water that you’re starting with. 
The Lifestraw go simplifies water purification by allowing users to scoop water from a river or other unsafe water source into the bottle, screw the lid on, and sip clean water through the mouthpiece. We have not had the opportunity to test the Lifestraw go. We would be interested in comparing it to the Sawyer Personal Water Bottle. Our next post will be a test of the Sawyer bottle.
A reverse osmosis system is typically installed under the sink, but you can install it where your water enters the house, so all your water is filtered for contaminants. RO filter cartridges provide the most effective filtration of any water purifiers. The membrane and filters remove up to 99 percent of contaminants such as arsenic, lead, ammonia and chlorine, as well as toxic fluoride, sodium, nitrates and heavy metals. The 6 stage RO filters provide a deep filtering process, leaving you reverse osmosis water, free of sediments and toxins. RO water is perfect for drinking, cooking and making ice.
Because the the semi-permeable membrane filters particles at the molecular level, reverse osmosis is extremely effective at removing bacteria, viruses, parasite cysts such as Giardia and Cryptosporidium, heavy metals such as lead and mercury, hard water minerals such as calcium and magnesium, and even fluoride and arsenic. It will not, however, remove certain pesticides and solvents small enough to pass through the membrane.
The process of distilling seawater into drinking water has been used by the Ancient Greeks since about 200 AD (Wikipedia). Many cultures throughout history have used distillation as an effective method of ensuring potable water. Although the materials used in the distillation process have changed over time, the science has remained the same, proving that distillation is a purification method that has stood the test of time.
Fluoride Removal: Although fluoride is added to water in many areas, some areas of the world have excessive levels of natural fluoride in the source water. Excessive levels can be toxic or cause undesirable cosmetic effects such as staining of teeth. Methods of reducing fluoride levels is through treatment with activated alumina and bone char filter media.
The tourist season got off to a grisly start this year in Gulf Shores, Ala. During a two-day period in early June, four men drowned after being caught in rip currents. The unusually strong currents were invisible, not even roiling the surface. Rip currents occur when water rushing back from the shoreline is channeled through a narrow gap between two sand bars, accelerating the outward flow.
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.
This system can purify up to 50 gallons of water per day and has 5 stages of filtration to remove up to 99 percent of TDS. For every gallon of purified water produced, there are 3 gallons of wastewater. This is an average conversion rate and is much better than some water filtration systems that have 4 or 5 gallons of wastewater for every purified gallon produced.

Filters have to be changed after every 6-12 months and RO-Membrane demands to change after every 2-3 years. The maintenance depends on the source of your water. If your water is more contaminated you may need to change it more than once every 6-12 months. The best part is transparent housing that helps you to identify the time when filters need to be changed.

Only a part of the saline feed water pumped into the membrane assembly passes through the membrane with the salt removed. The remaining "concentrate" flow passes along the saline side of the membrane to flush away the concentrated salt solution. The percentage of desalinated water produced versus the saline water feed flow is known as the "recovery ratio". This varies with the salinity of the feed water and the system design parameters: typically 20% for small seawater systems, 40% – 50% for larger seawater systems, and 80% – 85% for brackish water. The concentrate flow is at typically only 3 bar / 50 psi less than the feed pressure, and thus still carries much of the high-pressure pump input energy.
Distillation is a water purification method that utilizes heat to collect pure water in the form of vapor. This method is effective by the scientific fact that water has a lower boiling point than other contaminants and disease-causing elements found in water. Water is subjected to a heat source until it attains its boiling point. It is then left at the boiling point until it vaporizes. This vapor is directed into a condenser to cool. Upon cooling, vapor is reversed into liquid water that is clean and safe for drinking. Other substances that have a higher boiling point are left as sediments in the container.