Yet another quote from the Laws

Water is the greatest element of nutrition in gardens, but is easily polluted. You cannot poison the soil, or the sun or the air, which are the other elements of nutrition in plants, or divert them, or steal them; but all these things may very likely happen to water, which must therefore be protected by law.

And let this be the law: If anyone intentionally pollutes the water of another, whether the water of a spring, or collected in reservoirs, either by poisonous substances, or by digging, or by theft, let the injured party bring the cause before the wardens of the city, and claim in writing the value of the loss; if the accused be found guilty of injuring the water by deleterious substances, let him not only pay damages, but purify the stream or the cistern which contains the water, in such manner as the laws of the interpreters order the purification to be made by the offender in each case.

　　 - The Athenian Stranger, Plato’s Laws (845d-e)