4 fluid oz bottle. 10% solution of phosphoric acid.
The main use of phosphoric acid is in the soft drink industry where it is used to increase the acidity or "bite" of colas. In high concentrations it can even be used to remove rust. In brewing, phosphoric acid is used to increase the acidity of the water in all-grain brewing. It is added to the water before the brewing process begins.
Usage: Because phosphoric acid is being used to change the pH of water from a specific town, there is no precise dilution formula for its use. For complete accuracy, a pH meter can be used to determine when the desired pH level has been reached. Otherwise, the less scientific method of trial-and-error can be used.