The　naturally　occurring　water　has　frequency　dispersive　permittivity　at　microwave　frequencies　and　thus　is　a　promising　constituent　material　for　broadband　absorbers.　Here,　we　develop　water　as　the　dielectric　spacer　in　the　substrate　of　metal-backed　metamaterial　(MM)　absorbers.　The　designed　substrate　is　a　hybrid　of　water　and　a　low-permittivity　dielectric　material.　Such　a　design　allows　tight　packaging　of　water　and　easy　fabrication　of　the　absorber.　We　obtain　broadband　absorption　at　temperatures　of　interest　by　designing　the　hybrid　substrate　and　MM　inclusions.　Additionally,　the　absorption　performance　of　the　water-substrate　MM　absorbers　could　be　tunable　according　to　the　environment　temperature.　We　experimentally　demonstrate　the　broadband　and　thermally　tunable　absorption　performance.　We　expect　that　water　could　replace　dielectric　layers　in　other　structural　MM　absorbers　to　achieve　the　broadband　and　thermally　tunable　absorption　performance.　Published　by　AIP　Publishing.