From the complex to the simple, there are many types of home water filters available today. Water purification and filtration systems come in an assortment of styles, types, and price ranges, to suit every need. While a bottled water service that delivers purified water is an alternative, if used for everything it can be expensive. Yet buying your own water means hauling several gallons from the grocery store every week, then finding a place to store it. Home water filters are much more convenient.

The simplest home water filter device may be the water-filtering pitcher. Just fill the pitcher's special reservoir lid with tap water, and as the water runs through the filter into the pitcher, it is transformed into clean drinking water.

You can also purchase simple-to-use, easy-to-install home water filters that attach right to the tap. These are small canister filters containing carbon and other materials, which have a fitting to connect to the faucet spout. They are designed with a bypass valve to filter water only when necessary, such as for drinking or cooking. Simply screw the adapter onto the faucet. One click of the canister knob will give you filtered water, and the other will give you water for ordinary uses such as cleaning the sink. Most cartridges are rated between 100-300 gallons (378 liters - 1.1 kiloiters), and have built-in indicators to alert you when the filter is exhausted. Changing the filter is so simple anyone can do it.

A larger cousin to faucet home water filters, are purification systems that sit on the countertop, or under the sink. These home water filters may or may not be reverse osmosis (RO) systems. A water line feeds into the filter, and a small filter spout delivers purified water. Models vary widely. Some are ion-exchange filters. If you are worried about lime scale as well as other impurities, ion-exchange home water filters are the only filters that can completely remove calcium and magnesium, which cause lime scale. Canisters might be costly to replace, and will exhaust quicker in areas with hard water. Ion-exchange filters can also come in smaller, less expensive home water filters, and are even built into some coffee makers.

Of the countertop or under-sink home water filters that are RO filters, these use a dual-canister system: One canister is a particle filter and the other is a carbon filter. While these types of home water filters eliminate virtually all impurities, they also have some drawbacks. Making 1 gallon (3.78 liters) of RO water can take up to 10 gallons (38 liters) of tap water, depending on your local water supply. The "runoff" water is very hard, containing all the minerals removed from the purified water, and normally goes down the drain. Some people design a retaining tank to circulate this "wasted" water to their washing machine, or put it to some other use. RO makes the purest, softest water possible, at the highest price. It removes all contaminants, salts and minerals, including additives like fluoride.

Water distillers have long been popular home water filters. They boil water at such a high temperature that it becomes steam. The steam is reconstituted into pure, clean water. Distillers are larger than some other home water filters and are often connected to the water supply at the sink.

If you are really concerned about the quality of your water, you may want to consider purchasing home water filters that connect directly to your main water line. In this case every outlet in the house, including the shower and bath, will receive purified water. Some agricultural regions in the US require this type of filtering system by law, due to pesticides in the water table. These are also RO systems, and produce extremely soft, pure, distilled water. RO systems of this type are large and of all the home water filters, they are the most expensive--however, many people feel they are well worth the cost since they insure safe, clean, water throughout the entire home.