32 Pa. Stat. § 638
The board shall have the further power to revoke any permit granted under the terms of this act in case the water rights are not acquired within one year after the issuance of said permit, and said acquisition shall be null and void and of no effect, to the extent required to make water and water rights from such source available for acquisition under the terms of this act, if any actual taking of water be not made within the time specified in the permit not exceeding four years after the issuance of said permit. If the project required for the taking of water has been commenced in good faith or if the commencement thereof has been prevented by events beyond the control of the permittee, the board shall have the power, upon application of the permittee, to grant such extensions of said period as the board deems to be necessary to enable the permittee to complete the project required for the taking of water. If an actual taking is not made within the time specified in the permit or in any extension thereof, the water and water rights covered thereby shall become available for acquisition by other public water supply agencies under the terms of this act.
32 P.S. § 638