George purchased a derelict factory, which had been out of use for fifteen years. The factory had been used originally to produce chemicals. On site in one of the decaying outbuildings, George discovered a 500-litre tank, partially full of liquid. The look, feel, and smell confirmed it is toxic. George also asked a laboratory to confirm that the liquid was indeed toxic.

A small office building was located near the derelict factory. The small office building was built after the factory. The owner of the small office building told George that toxic liquid had been leaking from the derelict factory to the office building. The owner also threatened to take legal action against George.

As George was unsure as to how to respond to the owner of the small office building, George contacted you. As a lawyer, please advise George. Explain or define any legal term or concept that you use.