There are certain features that savvy consumers must look out for when they are shopping for under sink water filter systems. First and foremost, the price of the under sink water filter cartridge should be comparable to that of other types of filter systems, for example, refrigerator type filters. As the filter lasts for half a year, a consumer can expect an under sink water filter cartridge to cost about thirty dollars, which is how filters for other filter systems are typically priced. Since using an under sink water filter system costs only about six dollars per month, compared to over twenty dollars a month (assuming a usage rate of one case each week) for a bottled water system, the under sink water filter system is far more cost efficient.

An under sink water filter system whereby every component required for installation is included, is usually the best. A system such as this will have all the components required to connect the system to the pipes beneath the sink. Top of the line under sink water filter systems will almost certainly arrive with detailed instructions, which in turn means that anyone with the right wrench can easily install the system. So as to allow efficient use of the filtered water, an extra separate faucet for filtered water is also included in the system. This allows users to choose either filtered or unfiltered water, depending on the intended purpose; For example, filtered water being used for consumption and unfiltered water being used for washing, hence conserving the filtered water.

The water filtration capability of the best under sink water filter systems are commonly backed by guarantees. For example, some filter manufacturers guarantee a near perfect rate of removal for cysts and lead from the water supply. For instance, Giardia, a cyst in water, can cause a person to fall ill if it is not first removed from the drinking water. The filter must also remove the chlorine taste and odor in tap water, so as to make it as pure as possible to consume. Harmful chemicals and heavy metals like mercury, as well as herbicides and pesticides that leak into the water supply through farms should also be filtered by these systems.

Should a filter change be in order, a monitor which is present in many of the best under sink water filter systems alerts a user to change the filter. This intelligent design feature helps a user remember to change the filter every half year; a task that can so easily be forgotten in the hustle and bustle of life.