There is a (hand waving) 3 ft x 3 ft x 8 in
concrete slab with a gangly piece of metal sticking out of it that I suspect is a cistern cap. The questions that come to mind are:
1. How do I confirm it's actually a cistern? It's bound to be incredibly heavy.
2. If it is a cistern, is there anything I need to do to make sure it's safe to use, and, at that, how do you use it? (guess: need a pump)
3. Is it possible that it wasn't meant to be a cistern, just somewhere for flood
water to soak into and then disperse into the ground slowly? The slab is located near a street-fed drainage tube that floods when we get heavy rain.
If this isn't
enough information, let me know and I'll do my best to provide details!
Brian