A. Reverse Osmosis is a water purification process. The membrane actually repels contaminants away from its surface and attracts pure water molecules and oxygen to pass through. It also provides a mechanical filtration function, straining out particles down to a size of .0005 microns.
A. arbon filtration removes gaseous and low weight molecules such as chlorine, herbicides, pesticides and VOC’s. As water passes through the carbon, low weight contaminants adhere to the carbon. The carbon in a sense “holds on” to the contaminants. Carbon filters have a pore size of less than 1 micron to 50 microns, however it does not rely on the filtering/straining action alone…its main function is to actually adsorb (not absorb), or “grab” on to low weight and gaseous chemicals as they come into contact with the media. Carbon Block filters do a great job part in eliminating part of the spectrum of contaminants, but do not effectively remove metals and minerals. The process greatly improves the taste of the water, mainly because chlorine is a primary influence on water taste. If taste, odor and chlorine are the primary concerns, then a carbon block filter is the right choice.
A. The most popular solution is BOTH! When RO is combined with carbon filtration, the system reduces the entire spectrum of contaminants. It also oxygenates the water, which gives it a fresh taste.
RO “cleans water molecule by molecule!” It removes dissolved solids, particles that are in liquid form and smaller than even the water molecules themselves. RO purifies water by repelling contaminants away from the membrane surface. Even scientists don’t fully understand how it works: it is the only technology wherein contaminants are actually repelled away because of a molecular dynamic, and water and oxygen are drawn through. Mineral salts that are dissolved into liquid form and are smaller than the water molecules themselves, are otherwise virtually impossible to remove, except with distillation, are easily repelled and washed down the drain.
In some cases, depending on the local water supply, some customers prefer to just use carbon filtration to preserve the more “natural” state of the water with certain organic molecules left untreated. Carbon filtration does not rely on just filtration alone either…the carbon media actually “grabs” on to low weight and gaseous chemicals as they come into contact with it. The combination of RO and Carbon Filtration addresses the entire spectrum of contaminants. Plus, removing the metals and minerals that could impair the functioning of the carbon, makes the carbon all the more effective.
Over time, the combination of RO and carbon filtration has proven to be the best all around solution and value.
A. Water Softeners:-
Generally used at the Point of Entry of the house or site. Removes the hardness minerals, calcium and magnesium by the ion exchange process, replacing them with sodium from salt.Does not greatly improve water for consumption. Often called “working water”.
Generally POE; Can be just another term for a water softener but often includes other treatment medias such as activated carbon – mainly as a marketing tool. Typically overpriced.
Generally POU; Removes a very broad spectrum of impurities, comparable to RO, when used in conjunction with activated carbon. Costly energy usage, cleaning and awkwardness of locating most distillers have prevented them from becoming widely accepted consumer products. High quality distillers are particularly good choices when water supplies are of unknown quality or where micro biological contamination is present. The distiller market is growing steadily while the product is being continually improved. Distilled water tends to have flat taste because it is boiled “to death”.
Traditionally used for POE removal of iron, hydrogen sulfide and bacterial contamination. Recently POU products have come on the market for organic removal which ozone breaks down into harmless elements.Kills bacteria by adding an oxygen molecule.Ozone is basically an over excited oxygen molecule – 03 instead of 02. It is very aggressive and unstable. Once formed it does not last long and has a peculiar acrid smell.
Ozone is often used for micro biological control purposes in swimming pools. Some countries are currently experimenting with ozone for use as a disinfectant in public supplies. Like UV, ozone is primarily effective against micro-organisms, though it can also oxidize certain contaminants in much the same way as chlorine does.
Used for POU and POE as a means of controlling biological contamination. Inorganic an organic impurities are not affected. Products are being offered that combine carbon filtration and UV for more effective performance. Can be used as an adjunct to RO & Carbon filtration.
KDF is brass filings good for the removal of chlorine from shower water. Advantages are that it will not get destroyed in hot water (vs. carbon which will), so is good for shower filters. Disadvantages: As a drinking water system, it is not recommended. The brass filings could come out, and are not good to ingest, could stick into your insides! The KDF will codify ( turn into a brick) in low TDS areas, like the SF Bay Area. hot water prevents this (like the shower & tub type KDF only units)
Silver and other heavy metals (copper, zinc) deactivate bacteria (oligo-dynamic action) and creates a hostile environment for the growth of bacterial colonies. Silver impregnation does not kill or remove bacteria, but inhibits the growth of bacteria. Silver impregnation is used by NSA and some other companies, to inhibit the growth of bacteria. However, it will not actually do so past the first few servings of water. In order for it to inhibit bacteria growth for 6 months, it would have to have enough silver so as to be toxic to humans.
Iodinators & Brominators:-
As implied these units rely on the action of either iodine or bromine to kill bacteria. These products are only effective against micro-organisms and have no ability to remove other contaminants. The disadvantage of these systems is that traces of iodine or bromine, which are both halogens, are usually present in the filtered water. As these chemicals are themselves pesticides and suspected carcinogens they should not be consumed.
The removal of all ionized minerals and salts (both organic and inorganic) from a solution by a two phase ion exchange procedure: First, positively charged ions are removed by a cation exchange resin in exchange for a chemically equivalent amount of hydrogen ions. Second, negatively charged ions are removed by an anion exchange resin for a chemically equivalent amount of hydroxide ions. The hydrogen and hydroxide ions introduced in this process unite to form water molecules. This process is also called demineralization by ion exchange
A. If you live in the Bay Area, you may know that Bay cities are are all fortunate to be provided with some of the best quality municipal waters available. Mineral salts, heavy metals, organic chemicals, bacteria and other contaminants fall way below the EPA guidelines and limits for maximum contaminant levels. However, there remains a significant difference between water treated by reverse osmosis or even just carbon filtration, and tap water. Following are some things to consider when determining water treatment needs.
Total Dissolved Solids
The Total Dissolved Solids (TDS-heavy metals and solids that have dissolved into liquid form). Bay Area counts range from 100-1000 parts per million). A good water purifier will take out 95-98% of whatever TDS the water started with.
It is important to consider what happens to municipal treated water after it leaves the plant on its journey to your faucet. It wasn’t until 1986 that lead was regulated out of use for plumbing. Until July 1, 1986 lead was commonly used in pipes and in solder, and may have been used even later in some cases.
Marin Municipal Water District (MMWD) has done extensive research and is continuing to do research on lead pipes and lead solder. With the addition of lime and/or sodium hydroxide, the city has found that over a period of 5-7 years, the water naturally leaves behind a protective coating on the pipe walls, of calcium carbonate, which prevents the erosion and leaching of lead into the water. MMWD also adds zinc orthophosphate to the water to reduce corrosivity. People with homes built between Jan.1, 1983 and June 30, 1986, are potentially at risk, and should consider testing their water. People with houses built during that time may qualify to be included in MMWD’s study, and have their water sampled and tested by MMWD, through Oct. 1992 and later in 1993. Others, wishing to find out about the possibility of lead contamination in their pipes, may go to private labs, or get a test kit at The Water Store. (MMWD is also looking for people whose homes were built closer to the turn of the century, to study the composition of the pipes and effects of wear on the pipes over a long period of time.) A National Sanitation Foundation study certified Reverse Osmosis Systems will remove lead from drinking water.
Another area to consider is bacteriological. According to a study performed by Pierre Payment in Montreal, wherein 1,200 people in a suburban area had reverse osmosis systems installed, and were closely scrutinized over 18 months, along with 1,200 people who drank tap water. He found that the adults who drank tap water (treated at a state-of-the-art water treatment plant using chlorine, ozonation and filters for bacteria and viruses), had a 35% of greater chance of getting gastroenteritis, than those that had the RO systems. Of the children under 5 who were studied, there were 2-4 purified water drinking children getting gastroenteritus to 10 tap water drinking children who got sick. MMWD monitors and tests water at 109 locations throughout the district for bacteriological problems, and has consistently met the maximum contaminant level goals (non-enforceable) set by the EPA and the state. However, many people enjoy an added security of RO treatment.
Taste and Odor Factors
In addition to TDS, lead, and bacteriological considerations, there are also taste factors, which many people feel are important to consider. In addition to removing impurities that effect the taste of water, the process of reverse osmosis, doubles or triples the oxygen content surrounding the H2O molecule, in a process similar to the passing of water over rocks in a babbling brook. A charge is created by the movement of water across the surface of the mem-brane, which attracts the oxygen & pure H2O molecules to pass through the microscopic pores of the membrane. This is why we call RO water “fresh pressed” and why it has such a fresh, sweet taste.
Also effecting taste, are both Marin reservoirs’ characteristic “algae blooms,” as well as the chemicals added to reservoir water by the municipalities to suppress such growth, and chemicals added for other purposes. Among the chemicals added are; aluminum sulfate, chlorine, polymers, copper sulfate, sodium hydroxide and others, which are necessary, or helpful in treating water for large scale public use. These chemicals have a number of useful functions, such as helping to coagulate sediment for easy removal, disinfecting and destroying disease carrying bacteria, controlling corrosivity in the water to preserve pipes etc. and are all EPA approved for human consumption at low levels. However, some of these chemicals, such as chlorine, add an undesirable taste & odor to the water. During times of reduced water velocities due to conservation efforts of the public, MMWD has had to boost it’s frequencies, amounts & locations of chlorine added to the water (slow turnover in the distribution system creates conditions which are conducive to more bacteriological growth).
Chlorine may have other liabilities as well. It does its’ job by bonding with and oxidizing organic compounds. Oxidation can occur with the proteins and organic matter inside and outside our bodies as well, and has been associated with cell damage and reduced cell vitality by many nutritionists. Chlorine can also react with humic and fulvic acids to form undesirable organic by-products, such as Trihalomethanes (THMs). Various THMs have been classified by the EPA as either probable or possible human carcinogens, and have been associated with bladder and rectal cancer according to research performed by Dr. Robert Morris of the Medical College of Wisconsin.
The Environmental Protection Agency (EPA) & the State of California are responsible for setting standards for maximum contaminant levels for safe drinking water according to the ‘Safe Drinking Water Act’ of 1974. Although they have provided essential studies, guidelines and regulations on many substances, there are many new man made contaminants introduced into our ground and fresh waters every year. With the proliferation of industrial and agricultural toxins, it is near impossible to keep up, do the necessary studies, regulate and establish acceptable levels. This is illustrated in the case of lead, which, over the years, the MCL has been changed from 50 parts per billion (PPB), to a 0PPB goal currently with strict and frequent monitoring by the EPA, and not so long ago, was not regulated at all. Only in 1986 was lead outlawed in pipes & solder for new constructions. A substance that we now know to be a great threat to our health in any quantity, was once not even monitored. USPW recommends that if you want to set your own standards for water quality, that water be treated at the point of use, as well as at the municipal level. Many health practitioners recommend purified water, for its higher oxygen content, its purity and for its cleansing and replenishing effects.