Drinking water filters are water purification systems of varying degrees of sophistication that are designed to make tap water safe for drinking and cooking. There is a wide array of these filters, including charcoal and ceramic filters, de-ionization filtration systems, reverse osmosis filters, and UV radiation filtration systems.

Water filters and filtration systems are for the most part superior to using bottled water in place of tap water. Perhaps most importantly, you know what you're getting when you drink water from your faucet that has passed through your water filtration system. For another thing, drinking purified water from a reusable bottle or thermos is much more environmentally friendly (and, far less expensive in the long run) than constantly buying and discarding plastic water bottles.

You might think that all bottled water is the safe, clean, natural spring water that it purports to be. But there are great problems with this assumption. The bottled water industry has become a $100 billion a year industry, and therefore conflicts of interest can arise.

And according to investigations, they have. Much bottled "spring water" turns out to be just regular filtered tap water, but it still gets sold for the same high price and it still gets put into the discardable plastic bottles. It is questionable just how well the filtering process was done, since the bottled water industry is highly unregulated (meaning, it's not very transparent), and besides it's a lie to call filtered tap water spring water.

The plastic bottles pose problems of their own. These plastic bottles are needless to say non-biodegradable. They are fuel for the bad habits of litter bugs and lead to the polluting of the woods and waters, where they look ugly and can wreck animal habitats or even harm animals (animals may get their paws stuck in the bottle neck, etc). They are filling up landfills at rapid rates.

There are more recent allegations that water that has been sitting inside plastic containers for too long has absorbed low levels of lexan polycarbonate resin bisphenol-A (BPA). BPA is heavily used in the making of plastic and some studies have concluded that constant exposure to it, especially by way of the mouth and ingestion, can lead to poisoning of the endocrine system.

If you install a water filtration and purification system in your home or office, you know precisely how it's working; you can have it tested out at any time and you know up front what kind of tap water you have and what your system is intended to do. You also put the filtered tap water into reusable mugs or a thermos that is safer and far, far easier on the environment.