Water purifiers available in the United States range from simple pitchers to complex whole-house systems. The most common types include countertop filters, under-sink filters, reverse osmosis systems, UV purifiers, and alkaline water systems. These systems are designed to remove contaminants such as lead, chlorine, bacteria, viruses, and heavy metals from tap water, ensuring a healthier drinking experience.

The demand for water purifiers has been on the rise due to increasing concerns about water quality and the desire for healthier drinking water. According to the American Water Works Association, approximately 36 million Americans have tap water that exceeds the Environmental Protection Agency's (EPA) health standards. This has led to a growing market for water purification solutions.

Countertop filters are a popular choice due to their ease of use and relatively low cost. They typically attach to the faucet and filter water as it flows through. Examples include the Brita pitchers and the Pur faucet filters. These systems are effective at removing chlorine, lead, and other common contaminants but may not be as effective at removing viruses or certain heavy metals.

Under-sink filters are installed beneath the kitchen sink and provide filtered water directly from the tap. They are more effective than countertop filters and can remove a wider range of contaminants. Popular models include the Aquasana and Culligan systems. These filters often use a combination of activated carbon and other media to purify the water.

Reverse osmosis systems are among the most effective water purifiers available. They use a semipermeable membrane to remove up to 99% of contaminants, including dissolved solids, bacteria, and viruses. These systems are typically installed under the sink and require a separate faucet for filtered water. The EPA has recognized reverse osmosis as a treatment method for arsenic, fluoride, and lead, among other contaminants.

UV purifiers use ultraviolet light to kill bacteria and viruses in water. They are often used in conjunction with other purification methods, such as carbon filters. UV purifiers are effective at destroying microorganisms but do not remove chemical contaminants. They are commonly found in countertop and under-sink systems.

Alkaline water systems are designed to increase the pH level of water, making it more alkaline. Proponents claim that alkaline water can improve health and reduce the risk of certain diseases. However, scientific evidence supporting these claims is limited. Alkaline water systems typically use a combination of filters and electrolysis to achieve the desired pH level.

The market for water purifiers in the United States is expected to continue growing as consumers become more aware of the importance of water quality. According to Grand View Research, the global water purification market was valued at $15.8 billion in 2018 and is projected to reach $28.5 billion by 2025, with a compound annual growth rate (CAGR) of 8.1%. This growth is driven by rising health consciousness, environmental concerns, and technological advancements in water purification technology.