That's better. [] Short answer is maybe. There can be cisterns that are 200 years old but didn't get filled in until last week.
Only you and the shovel will know for sure.
people didn't throw junk in operating cisterns so there will be nothing thrown in it before it was abandoned. So if it was abandoned before 1900 it could be good.
Down here in Texas they are for sure worth digging. Most of them seem to have been abandoned around 1910-1920 and so we find late hutches, straight side Cokes, local embossed pharmacy bottles, and pottery jugs in them...as well as a lot of (whole) oil lamps. I guess they must have gotten electricity around then too and heaved their lamps in the cistern out back.