This chapter also has a time signature attached to it which ties it to the coming Messiah and the gospel age. Verse 1 is strongly alluded to by the Lord in John 7:37, and verse 7 is quoted by the Lord and applied to the events which will take place at his arrest, trial and crucifixion.
A fountain! Why, in the years of the temple, the water for cleansing and ablutions and washings has to be laboriously brought into the temple, bowl after bowl every day. But this is the fulfilment of the symbol. When Christ comes there will be no more carrying water for symbolic ablutions; there will be a fountain opened, a fountain of his mercy and grace and his shed blood, flowing for uncleanness: a copious cleansing fountain.