Q: How is my drinking water treated?
A: Your public drinking water is generally treated in the following way: Dirt and suspended particles are removed through a chemical process called coagulation. Then heavy particles are settled out of the water. The remaining water is passed through filters (sand, gravel, charcoal) to remove smaller particles. The final treatment step is disinfection with chlorine, chloramines or other disinfection method. Once purified, the water is either stored or pumped to the customer through a pipe distribution system.

This flowchart above shows the path that water takes from the intake of the water treatment plant (from the raw source water) to the storage tank, from which it is pumped to homes, businesses, and industries. The specific steps and their sequence may vary somewhat from one treatment plant to another. Many systems add additional chemicals (e.g., lime, orthophosphate) to minimize corrosion of pipes and thus reduce the amount of lead leaching into the water.

Q: How is drinking water purified?
A: Treating water to make it suitable to drink is much like wastewater treatment. In areas that depend on surface water it is usually stored in a reservoir for several days, in order to improve clarity and taste by allowing more oxygen from the air to dissolve in it and allowing suspended matter to settle out. The water is then pumped to a purification plant through pipelines, where it is treated, so that is will meet government treatment standards. Usually the water runs through sand filters first and sometimes through activated charcoal, before it is disinfected. Disinfection can be done by bacteria or by means of adding substances to remove contaminants from the water. The number of purification steps that are taken Depend on the quality of the water that enters the purification plant. In areas with very pure sources of groundwater little treatment is needed.

Q: How is drinking water quality protected?
A: All countries have their own legal drinking water standards. These prescribe which substances can be in drinking water and what the maximum amounts of these substances are. The standards are called maximum contaminant levels. They are formulated for any contaminant that may have adverse effects on human health and each company that prepares drinking water has to follow them up. If water will be purified to make it suitable to drink it will be tested for a number of dangerous pollutants, in order to establish the present concentrations. After that, one can determine how much of the contaminants have to be removed and if necessary purification steps can be progressed.

Q: How can I find out if my tap water is safe to drink?
A: Because of water's different sources and the different ways in which water is treated, the taste and quality of drinking water varies from place to place. Over 90 percent of water systems meet EPA's standards for tap water quality. The best source of specific information about your drinking water is your water supplier. Water suppliers that serve the same people year-round are required to send their customers an annual water quality report (sometimes called a consumer confidence report).

Q: How will I know if my water isn't safe to drink?
A: Your water supplier must notify you by newspaper, mail, radio, TV, or hand-delivery if your water doesn't meet EPA or state standards or if there is a waterborne disease emergency. The notice will describe any precautions you need to take, such as boiling your water. Follow the advice of your water supplier if you ever receive such a notice. The most common drinking water emergency is contamination by disease-causing germs. Boiling your water for one minute will kill these germs. You can also use common household bleach or iodine to disinfect your drinking water at home in an emergency.

Q: How can I help protect my drinking water?
A: Drinking water protection is a community-wide effort, beginning with protecting the source of your water, and including education, funding, and conservation. Many communities already have established source water protection programs. Call your local water supplier to find out if your community participates. You can also support efforts to improve operation, maintenance, and construction of water treatment processes.

Q: What about home water treatment units?
A: Most people do not need to treat their drinking water at home to make it safe. A home water treatment unit can improve water's taste, or provide an extra margin of safety for people more vulnerable to the effects of waterborne illness (people with severely compromised immune systems and children may have special needs). Consumers who choose to purchase a home water treatment unit should carefully read its product information to understand what they are buying, whether it is a better taste or a certain method of treatment. Be certain to follow the manufacturer's instructions for operation and maintenance, especially changing the filter on a regular basis. EPA neither endorses nor recommends specific home water treatment units. No single unit takes out every kind of drinking water contaminant; you must decide which type best meets your needs.

Q: How often do the filters need to be changed?
A: Filter life will vary in direct proportion to the amount of water used and the type and level of impurities in the water being processed. It is recommended that the filter be replaced when the first of the following occurs: (a) the unit's rated capacity is reached; (b) annually; (c) the flow rate diminishes (which occurs when the filter becomes clogged with particulate matter); or (d) the filter becomes saturated with bad tastes and odors. The filters can not be back flushed or rinsed and used again. Even if your filter is still white and the flow rate is still high, according to EPA and state health department guidelines, filters should always be replaced at least once a year, regardless of capacity.

Q: What are "point-of-use" and "point-of-entry" water quality improvement equipment and how does it differ from bottled water?
A: Point-of-use (POU) water quality improvement equipment is used to solve a specific problem at the exact location or point where a higher quality drinking water is desired. Drinking water at the kitchen sink or wet bar are examples. POU equipment includes various types of filtration and distillation devices. Point-of-entry (POE) equipment is generally located outside the home or business, and treated water is delivered to all inside taps. Examples are water softeners, iron filters and other types of equipment that are suitable for such utility purposes as laundry, dishes, cleaning and personal needs.

Q: Filters; what can they do?
A: There are many types of filters available in the market place today. We will try to group them by the method they use to filter water. Almost everyone has seen the ads for the filter that fits on the end of your kitchen sink or bathroom spigot. These filters usually use two basic types of filtration: a filter 'pad' catches the large (usually over 25 micron in size) particles or 'chunks', and a small amount of carbon to adsorb organics and/or chlorine. The main problem here is the flow rates at which they are expected to work at. The consumer expects to turn the tap on as normal and draw "filtered" water. To remove free chlorine, for instance, standard engineering practices set the maximum flow rate at 10 gallons per minute per square foot (144 square inches) of surface area of the carbon, 'if' you are using a standard 30" bed depth. To remove chloramines or organics, the maximum flow rate is set at 5 gallons per minute per square foot of surface area. If your spigot will provide a flow of 1.5 gallons per minute, what size filter do you need hanging on the end of that spigot to insure that the chlorine and organics will not be swept past through the filter, into your glass? If you purchase this type of filter, make sure it has a way of limiting the rate at which water passes through it.

Next comes the cartridge type filter. Most common are the 10 1/2 or 20 inch long filters. This type filter will usually have a removable housing, into which different types of "elements" can be placed. A sediment filter cartridge element can be manufactured to remove certain size particles and larger. Most elements for home use will indicate 30 or 50 micron and larger removal. More expensive elements, usually for industrial use, may indicate a particle size (in microns) and add the words "Absolute" after it. No, it isn't Vodka, it simply means that if it says 5 micron absolute, it means it! Very few particles larger than 5 microns will pass through the filter. The regular filter may say 25 microns, meaning that 'most' of the particles 25 microns and larger will be caught by the filter. Remember, there filters actually get better, or more effective, as they are used. The 'junk' in the water collects on the surface of the filter and becomes a part of the filter as well. As it builds up, progressively smaller and smaller particles are trapped, and the flow rate through the filter slowly diminishes. This slowing of the flow rate can be a source of problems to water using appliances in your home. If you use such a filter, regular changing of the filter element is very important. Elements for these filters can also be carbon (block or granular, or powdered), can be manufactured for use in hot water, can be ceramic, pleated as well as many other configurations. Some manufacturers are mixing a small amount of silver into the carbon to help prevent any bacteria growth in them. This has yet to be a proven methodology. In fact, make sure that such a filter doesn't give off more silver than is allowed, if not rinsed thoroughly prior to use, especially after a prolonged period of non-use. Remember, all filters, carbon especially, trap organics that bacteria feed on, and as the water sits without moving, they can multiply rapidly. Always change the elements on a regular, frequent basis.

Selective Resins: A relative newcomer to the market, some small filters now contain resins that only remove specific things from the water, such as Nitrates, Fluoride or Lead. Technology is rapidly changing in this area; If you have a need for such a device, you should ask for supporting test results from an independent testing lab to verify that the unit will perform as advertised. Many states now have legislation that requires such data be provided to you prior to purchase.

Deinonization: Used mainly in labs, manufacturing processes, or for serious aquarium owners, DI filters are actually more complex than a filter. True filters, unlike the selective resin and DI units, work on a mechanical basis: they just 'catch' the particles that are too large to fit through the spaces between the filter media. DI works by ion exchange, just like a water softener. Just as water softener exchanges sodium for hardness minerals, a DI unit will have two types of resin in it: Cation and Anion. Basically, the Cation resin (like in a water softener) removes the ions with a positive charge, while the Anion resin removes those ions with a negative charge. Instead of using salt as a regenerant, acid and caustic are used. Some small DI cartridges are sold as "throw-aways", others can be returned for regeneration and reuse. These small units can treat only small amounts of raw, city water. Usually, it is much more economical to pre-treat the water feeding a DI system with reverse osmosis water.

Distillation: One of the oldest methods for cleaning water is distillation. Simply put, you boil water, catch the steam, and condense it back into water. Theory is, the minerals stay behind in the boiling chamber, and only pure water ends up in your container. In the real world, most of those things do happen; but if you do not perform preventative maintenance on your still, you can get very poor results. Distillation will kill bacteria, viruses, cysts as well as remove heavy metals, organics, radionuclide, inorganics and particulates if properly maintained. One thing you must watch out for is VOC's (volatile organic chemicals). These chemicals have a lower boiling point than water (like benzene), and can vaporize and mix with the steam, carrying over into the product water. Some stills today have a volatile gas vent, a small hole at the top of the condensing coil that allows the venting of such substances. Many distillers have a carbon filter to "polish" the product water before use and to remove any VOC's that may carry over. The energy used to treat a gallon of water is usually about 3,000 watts, or about 25 cents per gallon (average) in the US. This treatment method requires that you 'plan ahead' and make and store water for use, which makes it somewhat less appealing. The more elaborate units will make and store water automatically, but raise the initial investment and maintenance of the equipment.

Reverse Osmosis: This is a process that is often described as filtration, but it is far more complex than that. We sometimes explain it as a filter because it is much easier to visualize using those terms. We should remember that osmosis is how we feed each cell in our bodies: As our blood is carried into the smallest of capillaries in our bodies, nutrients actually pass through the cell wall to sustain it's life. Reverse osmosis is just the opposite: We take water with "nutrients" (in this case, junk) in it, and apply pressure to it against a certain type of membrane, and, presto out comes "clean" water. Lets review the basics: If you take a jar of water and place a semi-permeable membrane (like a cell wall? or a piece of skin?) in it, dividing the jar into two sections, then place water in both sides to an equal level, nothing happens. But, if you place salt (or other such substance) into one side of the jar, you will notice that, after awhile, the water level in the salty side begins to rise higher as the unsalted side lowers. This is osmotic pressure at work: The two solutions will continue to try to reach the same level of salt in each side by the unsalted water passing through the membrane to dilute the salty water. This will continue until the "head" pressure of the salt water overcomes the osmotic pressure created by the differences in the two solutions. Researchers have discovered that if we take that membrane and feed water with sufficient pressure to overcome the osmotic pressure of the two waters, we can 'manufacture' clean water on the side of the membrane that has no pressure. We sometimes say we "filter" the water through the membrane. Depending on the membrane design, and the material it made from, the amount of TDS (total dissolved solids) reduction will range from 80 to over 99 per cent. Different minerals have different rejection rates, for instance, the removal rate for the membrane we are looking at now is 99.5% for Barium and Radium 226/228; but only 85.9% for Fluoride and 94.0% for Mercury. Removal rates are very dependent on feed water pressures, and some membranes are not tolerant to high or low pH. For home use, it is important to make sure you get an RO System; i.e., sediment pre-filter, a carbon pre-filter, membrane, storage tank and post carbon filter. Some of these filters may be combined into one, i.e., the pre-filter may be both a particulate and a carbon filter. A lot of comments have been made concerning the wasting of water by an RO. True, the old style units with the early type membranes were more prone to becoming plugged, or fouled by the "junk" they removed from the water. To help keep this from happening, a small amount of water was allowed to run across the membrane to help carry away those impurities to drain. Early designs only recovered 1 gallon of good water for every 4-8 gallons used to keep the membrane clean. And when your storage tank was full, water still ran to the drain because the early membranes were made of a material that the little bugs in your water supply (no, not pathogens, or dangerous to you in small numbers) loved to eat! So to prevent that, we just let the water run so they couldn't have time to stop and eat. Now membranes are made that not only recover a much higher percentage of the feed water, but the bugs don't eat them! Newer systems not only recover more water to begin with, they may also have a shut off device that stops all water flow when the storage tank is full. Actual recovery rate is dependent on several factors, including the TDS, and just what the TDS is composed of, in your feed water. Temperature and pressure also have a big effect on the amount of product water you can make in a given period. Remember, all RO units are normally rated using a feed water temperature of 77 degrees F, is your feed water temperature that high?

Q: What do I do if my drinking water is polluted?
A: Be glad you found out now if your drinking water is toxic so you can begin saturating your body with pure water. If your drinking water is polluted or has heavy metals within it, try the following:
r Rent or buy a water cooler and have the highest quality spring water delivered to your home. Keep the cooler full of cool water and teach your children to drink as many glasses a day of fresh water above soft drinks, too much iced tea, or sugary boxed-type drinks.
r Install a water purifier on your kitchen sink, on the bathroom faucets, and on the shower heads.
r Install a household water purification system on the main water main going into your home, if possible. It is worth the investment.
r Drink water, water, water all day every day.