Attosecond pulses at photon energies that cover the principal absorption edges of the
building blocks of materials are a prerequisite for time-resolved probing of the triggering
events leading to electronic dynamics such as exciton formation and annihilation. We
demonstrate experimentally the isolation of individual attosecond pulses at the carbon K-shell
edge (284 eV) in the soft X-ray water window with pulse duration below 400 as and with a
bandwidth supporting a 30-as pulse duration. Our approach is based on spatiotemporal
isolation of long-wavelength-driven harmonics and validates a straightforward and scalable
approach for robust and reproducible attosecond pulse isolation