Abstract: A downspout water conservation diversion adaptor is provided for insertion within the lower part of an upstanding downspout and is selectively operable to divert water flowing downward through the downspout laterally outwardly of the adaptor and along a building wall outwardly beyond which a roof eaves projects for irrigation of ground vegetation disposed beneath the eaves. The adaptor is constructed to automatically bypass excess water flowing downwardly to the adaptor, in excess of that water which may be laterally outwardly directed from the adaptor, in a manner such that the excess water is discharged from the bottom of the downspout.