What is the distance and the approimate time from Gubel Water town to Beijing downtown?

The distance is about 87 miles (140km).

By bus: take bus line Mi 55 from the town to Miyun Bus Station (about 50 minutes). Then, change to bus line 980 Express to downtown Beijing (about 2 hours).

By taxi: it takes about 2 hours by car. The fare may be around CNY 500. ;)

then take bus 980 or 980 Express from Dongzhimen Transit Hub to Miyun Bus Station. transfer to bus . Then walk to the entrance of Gubei Water Town where you will find the visitor center to buy ticket.