An identical covered jar is illustrated in Blue and White Porcelain with Underglazed Red (III) - The Complete Collection of Treasures of the Palace Museum, Hong Kong, 2000, pl. 158; and another was sold in our New York Rooms, 21 March 2002, lot 215.
The five characters on the shoulder may be translated 'Finest Spring Water Under Heaven'. Both of the lengthy inscriptions appear to have been copied from text written by the Qianlong emperor. The shorter of the two texts, dated to the renwu year (1762), is a poem praising the Zhongling spring; while the longer inscription is an ode inspired by the emperor's visit to the spring and having tasted the fresh water at its source.
These jars were made specifically for the storage of water for consumption by the Empress Dowager Cixi. The water was collected from Yuquan Shan, north of Beijing, and delivered daily to the palace. The shape of the jar, its small mouth and snugly fitted cover that also functions as a stopper, were all designed to keep the contents well sealed and, therefore, pure.