Tonic water and is used mostly for its flavor. As a result of the lower quinine content, it is less bitter, and is also usually sweetened, often with high-fructose corn syrup or sugar. Some manufacturers also produce diet (or slimline) tonic water, which may contain artificial sweeteners such as aspartame. Traditional-style tonic water with little more than quinine and carbonated water is less common but may be preferred by those who desire the bitter flavor. In the United States, the US Food and Drug Administration (FDA) limits the quinine content in tonic water to 83 ppm (83 mg per liter if calculated
Hard water the effects of hard water on the surfactants. For this reason, water softening is often unnecessary. Where softening is practised, it is often recommended to soften only the water sent to domestic hot water systems so as to prevent or delay inefficiencies and damage due to scale formation in water heaters. A common method for water softening involves the use of ion exchange resins, which replace ions like Ca by twice the number of monocations such as sodium or potassium ions. Washing soda (sodium carbonate - NaCO) is easily obtained and has long been used as a water softener for