I say, and with God's help: If it is known that its foulness is due to impurity in it, then it is not permissible to perform ablution from it. If it is known that its foulness is not due to impurity, then it is permissible to perform ablution from it, assuming that its foulness is due to prolonged stay. Refer to: Sharh Al-Wiqayah, pages 96-97, and God knows best.