What is the ruling on two small ponds (*ghadeerayn*) connected by a channel containing water?

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When two small ponds are connected by a channel containing little or much water, they are treated as a single body of water, sharing the ruling of one pond. If the combined volume reaches two *qullahs*, neither pond becomes impure except through change in quality. If the combined volume does not reach two *qullahs*, each pond becomes impure by the mere falling of filth into either one, as they constitute connected, stagnant water resembling a single pond.