  We develop an all-electron path integral Monte Carlo (PIMC) method with
free-particle nodes for warm dense matter and apply it to water and carbon
plasmas. We thereby extend PIMC studies beyond hydrogen and helium to elements
with core electrons. PIMC pressures, internal energies, and pair-correlation
functions compare well with density functional theory molecular dynamics
(DFT-MD) at temperatures of (2.5-7.5)$\times10^5$ K and both methods together
form a coherent equation of state (EOS) over a density-temperature range of
3--12 g/cm$^3$ and 10$^4$--10$^9$ K.
