It's a quote from the HBO drama Gentleman Jack
The speaker came up with the idea below after inspecting her coal pit.
-So there I am, knee-deep in water, and it struck me that I ought to add another clause to the lease with the Rawsons to stop them from turning the water back on me when they've finished loosening my coal.
What's the meaning of turning the water back on me? Does that mean setting somebody up or something water-related?
Because that's not an idiomatic phrase with a commonly accepted meaning it's hard to say what the speaker meant without having more context. We can look at it and get some clues, though.
The speaker is knee-deep in water in her own coal pit. This situation gives her an idea. Unless a person is swimming or fishing for pleasure, being knee-deep in water is probably not a good situation. So I'm guessing it's a bad situation that gives her this idea. Because she says, 'So there I am..' it's probably also an unexpected situation. So she is suddenly realizing that there's a bad situation in the coal pit.
Her idea is to force the Rawsons not to turn the water back on her by adding a clause to the lease. She's afraid that she will experience the same kind of bad situation because of the Rawsons that she sees in the coal pit. They will do the same thing to her that they're doing to the coal pit. This could be figurative - they might ruin her like they're ruining the coal pit. Or it could be literal - they might let the water out of the coal pit and flood her living space.
That's all I can guess from this small bit of text.
