This is my second RO-PH90 system. Simply one of the best systems on the market, in my opinion. Uses genuine Dow filmtec reverse osmosis membrane. As anyone familiar with RO knows, filmtec membranes are the gold standard and rank among the elite in rejection rates. This is not your generic RO bought in a hardware store, although some large chains carry it. Input TDS = ~225 ppm, output TDS = ~15-20ppm. Does the job. Have not tested PH yet. Water tastes great as it does with my first system. Change your pre filters once per year or at the recommended %TDS interval and expect this RO membrane to last its full schedule of 3-5 years. This is very important. Incoming water pressure must be at least 50psi in my opinion, for this system to operate as intended. At 75psi, outgoing pressure is like a dream, even with 1/4'' stock tubing. ... full review
Many books and articles suggest this method as a safe alternative when lacking water filtration or purification methods. Without testing equipment some methods are difficult to prove. Norseman of Survivology 101 posted two great blogs which include testing done while he trained with the Norwegian school of Winter Warfare. The testing shows that the Mash or Seep showed zero improvement in lowering the bacterial count. Norseman is a retired Marine who held a Scout Sniper Survival instructor position at the First Marine Division, and SERE instructor.
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.
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.
Waters exiting the flocculation basin may enter the sedimentation basin, also called a clarifier or settling basin. It is a large tank with low water velocities, allowing floc to settle to the bottom. The sedimentation basin is best located close to the flocculation basin so the transit between the two processes does not permit settlement or floc break up. Sedimentation basins may be rectangular, where water flows from end to end, or circular where flow is from the centre outward. Sedimentation basin outflow is typically over a weir so only a thin top layer of water—that furthest from the sludge—exits.
Chlorine is a powerful chemical that has been in use for many years to treat water for home consumption. Chlorine is an effective water purification method that kills germs, parasites and other disease-causing organisms found in ground or tap water. Water can be purified using chlorine tablets or liquid chlorine. As an off-the-shelf water purification product, chlorine is cheap and effective. However, caution should be taken when using chlorine liquid or tablets to treat drinking water. For example, people suffering from thyroid problems should talk to a medical practitioner before using this product. When using chlorine tablets, it is important to apply them in heated water, as they dissolve well in water that is at 21 degree Celsius or higher. Chlorine tablets kill all bacteria leaving your water clean and safe.
U.S. Army Major Carl Rogers Darnall, Professor of Chemistry at the Army Medical School, gave the first practical demonstration of this in 1910. Shortly thereafter, Major William J. L. Lyster of the Army Medical Department used a solution of calcium hypochlorite in a linen bag to treat water. For many decades, Lyster's method remained the standard for U.S. ground forces in the field and in camps, implemented in the form of the familiar Lyster Bag (also spelled Lister Bag). This work became the basis for present day systems of municipal water purification.
The Metropolis Water Act introduced the regulation of the water supply companies in London, including minimum standards of water quality for the first time. The Act "made provision for securing the supply to the Metropolis of pure and wholesome water", and required that all water be "effectually filtered" from 31 December 1855.[41] This was followed up with legislation for the mandatory inspection of water quality, including comprehensive chemical analyses, in 1858. This legislation set a worldwide precedent for similar state public health interventions across Europe. The Metropolitan Commission of Sewers was formed at the same time, water filtration was adopted throughout the country, and new water intakes on the Thames were established above Teddington Lock. Automatic pressure filters, where the water is forced under pressure through the filtration system, were innovated in 1899 in England.[37]
Many books and articles suggest this method as a safe alternative when lacking water filtration or purification methods. Without testing equipment some methods are difficult to prove. Norseman of Survivology 101 posted two great blogs which include testing done while he trained with the Norwegian school of Winter Warfare. The testing shows that the Mash or Seep showed zero improvement in lowering the bacterial count. Norseman is a retired Marine who held a Scout Sniper Survival instructor position at the First Marine Division, and SERE instructor.
Radium Removal: Some groundwater sources contain radium, a radioactive chemical element. Typical sources include many groundwater sources north of the Illinois River in Illinois, United States of America. Radium can be removed by ion exchange, or by water conditioning. The back flush or sludge that is produced is, however, a low-level radioactive waste.

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.
Pure water has a pH close to 7 (neither alkaline nor acidic). Sea water can have pH values that range from 7.5 to 8.4 (moderately alkaline). Fresh water can have widely ranging pH values depending on the geology of the drainage basin or aquifer and the influence of contaminant inputs (acid rain). If the water is acidic (lower than 7), lime, soda ash, or sodium hydroxide can be added to raise the pH during water purification processes. Lime addition increases the calcium ion concentration, thus raising the water hardness. For highly acidic waters, forced draft degasifiers can be an effective way to raise the pH, by stripping dissolved carbon dioxide from the water.[4] Making the water alkaline helps coagulation and flocculation processes work effectively and also helps to minimize the risk of lead being dissolved from lead pipes and from lead solder in pipe fittings. Sufficient alkalinity also reduces the corrosiveness of water to iron pipes. Acid (carbonic acid, hydrochloric acid or sulfuric acid) may be added to alkaline waters in some circumstances to lower the pH. Alkaline water (above pH 7.0) does not necessarily mean that lead or copper from the plumbing system will not be dissolved into the water. The ability of water to precipitate calcium carbonate to protect metal surfaces and reduce the likelihood of toxic metals being dissolved in water is a function of pH, mineral content, temperature, alkalinity and calcium concentration.[5]
Water filters can come in smaller, portable forms which are convenient for travel and outdoor activities. Those who go hiking and backpacking often come across bodies of fresh water such lakes and rivers. While lakes and rivers are considered fresh in comparison to the seawater, they still need to be filtered before drinking due to the presence of sediment and potential bacteria. Having a portable water filter handy will eliminate the worry of ingesting harmful contaminants such as bacteria, parasites, sedimentary rock. Read our article on portable water filters for a detailed guide on how they work and which brands to use.

Radium Removal: Some groundwater sources contain radium, a radioactive chemical element. Typical sources include many groundwater sources north of the Illinois River in Illinois, United States of America. Radium can be removed by ion exchange, or by water conditioning. The back flush or sludge that is produced is, however, a low-level radioactive waste.

The most common disinfection method involves some form of chlorine or its compounds such as chloramine or chlorine dioxide. Chlorine is a strong oxidant that rapidly kills many harmful micro-organisms. Because chlorine is a toxic gas, there is a danger of a release associated with its use. This problem is avoided by the use of sodium hypochlorite, which is a relatively inexpensive solution used in household bleach that releases free chlorine when dissolved in water. Chlorine solutions can be generated on site by electrolyzing common salt solutions. A solid form, calcium hypochlorite, releases chlorine on contact with water. Handling the solid, however, requires more routine human contact through opening bags and pouring than the use of gas cylinders or bleach, which are more easily automated. The generation of liquid sodium hypochlorite is inexpensive and also safer than the use of gas or solid chlorine. Chlorine levels up to 4 milligrams per liter (4 parts per million) are considered safe in drinking water.[12]
Treatment with reverse osmosis is limited, resulting in low recoveries on high concentration (measured with electrical conductivity) and fouling of the RO membranes. Reverse osmosis applicability is limited by conductivity, organics, and scaling inorganic elements such as CaSO4, Si, Fe and Ba. Low organic scaling can use two different technologies, one is using spiral wound membrane type of module, and for high organic scaling, high conductivity and higher pressure (up to 90 bars) disc tube modules with reverse-osmosis membranes can be used. Disc tube modules were redesigned for landfill leachate purification, that is usually contaminated with high levels of organic material. Due to the cross-flow with high velocity it is given a flow booster pump, that is recirculating the flow over the same membrane surface between 1.5 and 3 times before it is released as a concentrate. High velocity is also good against membrane scaling and allows successful membrane cleaning.
Chlorine is effective against bacteria and most viruses. Norovirus, an intestinal disease that causes diarrhea, is particularly resistant to chlorine and will require the water to sit twice as long instead of the standard 30 minutes before consumption. Giardia, a parasite with a protective coating, will survive in chlorine treated water for 45 minutes before its safe to drink.
While reverse osmosis systems are widely used for industrial and commercial purposes, smaller home units can be purchased and installed under the kitchen sink and dispensed through the faucet. Home RO units typically run on a 3-stage system which includes a carbon filter, RO membrane, and re-mineralizing filter for taste. Some systems can include 5, 7, or even 10 stages. While the additional stages offer extra benefits such as pH level balance and UV filtration, a simple 3-stage system has everything required to produce pure, drinkable water. RO systems require frequent maintenance and replacement of filters in order to keep it functioning properly. Read our article on reverse osmosis systems for home use for a detailed guide on how they work and which brands to use.
Some small-scale desalination units use 'beach wells'; they are usually drilled on the seashore in close vicinity to the ocean. These intake facilities are relatively simple to build and the seawater they collect is pretreated via slow filtration through the subsurface sand/seabed formations in the area of source water extraction. Raw seawater collected using beach wells is often of better quality in terms of solids, silt, oil and grease, natural organic contamination and aquatic microorganisms, compared to open seawater intakes. Sometimes, beach intakes may also yield source water of lower salinity.
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