Tap water quality can vary depending on the water source, treatment processes, distribution system, plumbing infrastructure, and local environmental conditions. Common water-quality concerns may include sediment, chlorine, metals, microorganisms, and other contaminants. Reviewing local water-quality reports and conducting appropriate testing can help consumers understand what is present in their tap water. Where treatment is required, the filtration system should be selected according to the specific contaminants identified. Different technologies are designed for different purposes, so consumers should check independent certifications and verified performance claims.