A spring, however, or a cistern for collecting water remains clean, but anyone who touches one of these carcasses is unclean. (NIV)
Yet a spring or a cistern or reservoir of water shall be clean; but whoever touches their carcass shall be unclean. (AMP)
Nevertheless a fountain or pit, wherein there is plenty of water, shall be clean: but that which toucheth their carcase shall be unclean. (KJV)