上次有人说因为减少铅含量,所以有意调到 9.2-9.4 。不知真假?
搜到的:
The City adjusts the water supply pH to 9.2 – 9.4 to minimize the amount of lead and other metals that can dissolve into tap water. The City routinely monitors tap water lead concentrations in older homes through an extensive water sampling and testing program.