This article came directly from the EPA Newsroom  It's worth a read.
(Washington, D.C. - Jan. 17, 2007) Today 10 universities received grants from EPA for research to develop better methods for detecting harmful organisms in drinking water, including viruses, bacteria and protozoa. The grants, awarded through EPA's Science to Achieve Results (STAR) research grants program, are aimed at ensuring that the United States has the safest drinking water in the world.

"These five million dollars in grant money are an example of how EPA puts science to work to protect human health," said Dr. George Gray, EPA's assistant administrator for research and development.

Every year, there are cases of gastrointestinal (GI) illnesses in the United States associated with drinking water. EPA's sponsored research will result in faster and more sensitive tests for local drinking water facilities to use in detecting pathogens. The sooner a contaminant is identified, the faster a facility can act to contain the problem, and thereby reduce any health risks to the public.

The grants were awarded to the following universities for research on:

• Tufts University, North Grafton, Mass., $600,000 – a rapid (less than four hours) method for detection of disease-causing organisms by drinking water facilities.
• University of Arizona, Tucson, Ariz., $466,817 – nanotechnology application for the rapid and economic concentration of GI viruses, parasites, and bacteria.
• Metropolitan Water District of Southern California, La Verne, Calif., $600,000 – use of molecular biology to extract nucleic acids from waterborne organisms, allowing facilities to detect a broad range of potential disease-causing organisms
• Michigan State University, East Lansing, Mich., $600,000 – new method that can simultaneously detect 20 waterborne pathogens in source and drinking water.
• University of Washington, Seattle, Wash., $597,987 -- rapid, sensitive method to detect and measure known and emerging pathogens.
• Johns Hopkins Bloomberg School of Public Health, Baltimore, Md., $600,000 – new method to improve measurement of viruses and protozoa in drinking water, that could replace the current reliance on bacterial indicators only.
• University of California, Riverside, Calif., $600,000 – real-time method to detect and measure intestinal viruses in drinking water.
• Drexel University, Philadelphia, Pa., $566,714 – sensors that can detect pathogens such as Cryptosporidium without a concentration or filtration step.
• Michigan State University, East Lansing, Mich., $600,000 – real-time tool to determine whether drinking water contains bacterial contaminants.
• University of North Carolina, Chapel Hill, N.C., $600,000 – real-time tool to detect multiple classes of microbial pathogens

Tap Water Filters & Purifers are recommended particularly in the following situations:  A small quantity of pure filtered water is all you need and you do not want a  Reverse osmosis system permanently installed , you have fairly soft water of a reasonable quality and so you will get a higher return per cartridge, or if you want to further purify water from a basic RO unit.

The main features of these units are as follows: attaches easily to your faucet in seconds; removes most sediments, chlorine, chloramine, heavy metals, organic chemicals, and inorganic ions from tap water.

Where you can go to get one

This sort of device can be found in most any home center, or online and so you should not find this process to be especially difficult, however you should still take time and consideration in your decision, as you not only want to get the best unit possible  but you also want to end up with the best quality water filter you possibly can.

If you still can't decide whether or not you need some sort of water filter in your home read on.

Even if the water leaves the source in a relatively clean state, the practice of making water safe to drink actually involves adding large amounts of extremely poisonous chemicals to it. Tap water is treated with a large number of chemicals in order to kill bacteria and other microorganisms. And, water travels through pipes, which may have been underground for a very long time. It is almost impossible for the water not to become contaminated by something undesirable.  In addition, it may contain other undesirable contaminants like toxic metal salts, hormones and pesticides, or it may become contaminated by chemicals or microbes within pipes (e.g. lead, bacteria, protozoa).

Typical Tap Water Content:

• Chlorine  Fluorine compounds
• Trihalomethanes (THMs)
• Salts of: arsenic,  radium,  aluminum,  copper,  lead,  mercury,  cadmium,  barium
• Hormones
• Nitrates
• Pesticides

Still think you don't need your water filtered?

A refrigerator water filter is installed in the door of a refrigerator, and filters impurities such as chlorine, VOCs and lead out the water, making it pleasant and healthy to drink. Water filters for the refrigerator are about the same as ice maker water filters, it is only a matter of the sort of appliance they are cleaning water for. Recommended replacement is every 6 months for most of the Built-In refrigerator water filters.
Built-In refrigerator water and icemaker filters are a great idea and they have been embraced by most of the major refrigerator makers including: GE, Frigidaire, Whirlpool, Maytag, Kenmore, Sears, Samsung, and LG. This type of filter is the easiest to identify and replace. Drinking water filters for the refrigerator are designed to attach on the back of the plumbed refrigerator and provide filtration for drinking water and ice dispensed via your plumbed fridge. If you want water that is filtered and cold, a refrigerator water filter is the water purifying device for you.

Choosing a water filtration system for your home can be quite daunting. With so many products available on the market today, where do you start. What kind of system do you need, how much should you spend, what works and what doesn’t, the best manufacturer.

Reverse Osmosis, Carbon filtration, Portable Water Systems…. The list goes on and on. We break it down for you step by step starting with what you need based on what substances are in your water supply. Don’t worry, we tell you how.

A comprehensive look at what is available that will save you time and money!

If you have concerns about a wide range of contaminants in your drinking water such as chemicals and heavy metals like lead, you may want to consider a reverse osmosis water filtration system.

The reverse-osmosis membrane acts like an very fine filter to create drinkable water contaminated water. The membrane has microscopic openings that allow water molecules, but not larger compounds, to pass through.

The system is usually located beneath the kitchen sink since it is used to treat water for drinking and cooking purposes. Reverse-Osmosis systems consist of the pre-filter, RO membrane unit, a pressurized storage tank for the treated water, a post-filter and a separate delivery tap for the treated water supply.

The reverse osmosis water filters do a very good job but can get pricey, so it is a good idea to shop around and compare.