Russia's West Siberian Lowland (WSL) contains the most extensive peatlands on Earth with many underlain by permafrost. We present a new database of 12 705 measurements of vertical water content and bulk soil properties from 98 permafrost and non-permafrost cores collected in raised bogs and peat plateaus across the region, together with in-situ measurements of surface moisture and thaw depth, botanical descriptions of dominant surface vegetation species assemblage, and field notes. Data analyses reveal significant contrasts (p < 0.01 to p < 0.0001) between permafrost and non-permafrost sites. On average, permafrost WSL peatlands exhibit drier surfaces, shallower depth, lower organic matter content and higher bulk density than do non-permafrost sites. Peat bulk density and ash-free density increase with depth for non-permafrost but not for permafrost sites. Gravimetric water content averages 92.0% near the surface and 89.3% at depth in non-permafrost, but 81.6% and 85.4%, respectively, in permafrost, suggesting that the disappearance of permafrost could produce moister surfaces across the WSL. GIS extrapolation of these results suggests that WSL peatlands may contain ~1200 km3 of water and ice, a large storage equivalent to ~2-m average liquid water depth and approximately three times the total annual flow in the Ob' River. A global estimate of ~6900-km3 subsurface water storage for all northern peatlands suggests a volume comparable to or greater than the total water storage in northern lakes. The database is freely available as supplementary material for scientific use at http://onlinelibrary.wiley.com/doi/10.1002/ppp.735/suppinfo. Copyright © 2012 John Wiley & Sons, Ltd.