Tap water almost always has some levels of contamination and is bad for your health to drink directly. The contaminants come from aging pipelines and storage tanks, such as dirt, algae, rust and worms; or from the water plant, such as residual chlorine, chloramine, or other disinfectant byproducts. In developed countries, high levels of disinfectant at the point of use causes bad tastes and may lead to chronic diseases if drank constantly. In less developed regions, drinking tap water may cause severe illness due to the lack of disinfection. A water filter is much more convenient, economic and environment-friendly than buying bottled water.