Tap water is not as safe for drinking as many people assume in many places and as many governments tell us. Government bureaucrats make it seem as if their regulatory efforts are perfect and complete, but there are many gaping holes in them.

Tap water is often "cleansed" with chlorine. Once thought to be a great and benign water cleanser even for drinking water, chlorine has now been linked in numerous studies to causing cancer if consumed for an extended period of time. Tap water delivery systems of cities, towns, and municipalities are often out of date, dirty, and rusting and pass along filth such as rust into the tap water supply. Government regulations also arguably do not set low enough "safe levels of consumption" for potential harmful ingredients in tap water (if there really are safe levels of at least some of them).

Other times, especially in more rural settings, tap water is not filtered at all. Microbes, dirt, fungi, spores, viruses, even toxins from heavy metals may well be lurking in tap water.

Due to these hazards, water filtration systems are needed by at least the vast majority of people.

Water filtration systems force tap water to pass through a filter, typically a charcoal or ceramic filter, and when it does the filter removes impurities from the water but still allows the cleansed water to flow through to the tap (some water filters are also placed right at the tap). Different filters are used for different water purification needs, and some of them improve the taste of your water.

One basic type of water filtration system is the faucet filtration system. This is the kind your hook up right to your tap. As the water flows from your tank to your tap, the filter cleanses it and makes it healthy for consumption. There is typically a loss of water pressure from this, since the filtering membrane naturally slows the water flow down, so if you are going to use the water for a non-consumption purpose such as washing your hands or doing dishes you can turn off the faucet filter.

With under-the-sink filtration systems the filter is installed such that the water passes from the water tanks and through the filtration system before reaching the tap, so that what leaves the tap is already purified. Some people prefer these or need these because they can be used for getting rid of a wider array of potentially harmful things than can faucet filters.

Countertop or "jug" filtration systems are containers into which you pour unfiltered tap water. But when you pour out this tap water from the container in order to take a drink, the container itself filters the water on the spot.

Water main filtration systems are the most sophisticated and are intended to be a one-stop system that filters all of the water in your home or office. These are used not only for making water suitable to drink but for making all of your water cleaner all the way around for all purposes. Homes built in places with very high levels of bacteria or iron content in the water need systems like this.