jiǎndān yī jù qīng yīdiǎn huò shuǐ liáng yīdiǎn diànyuán tōngcháng néng mǎshàng tiáozhěng

简单一句“轻一点”或“水凉一点”，店员通常能马上调整。

With a simple "a bit gentler" or "cooler water," the staff can usually adjust right away.