Originally Posted by lewishowardm3
Thanks for the reply. Although I don't know how they test the water in the US but it seems to me that alkalinity is only tested once a year here on the UK so do you think that it must not change much otherwise they would test it more frequently?
Don't know but I'll guess they test it more often than that. They may just not make that information available. OTOH it may be quite constant. You could call or e-mail the supplier and ask if it is variable and if so how much.
Alkalinity is a very simple thing to test. You can buy inexpensive test kits at aquarists, hardware stores, scientific supply houses etc. Or you can test it simply by adding 0.1 N HCl to 100 mL of water until the pH reaches 4.5 as indicated by a pH meter or indicator dye such as brom cresol green - methyl red. The alkalinity, in units of ppm as CaCO3, is the number of mL of acid it takes.
Some breweries and brewers simply add enough acid (in the US usually phosphoric, over there you have CRS) to bring the mash water to pH 5.5. In so doing they are eliminating most (89%) of the alkalinity and, at the same time, measuring it if they keep track of the amount of acid required.