The idea that Na⁺ retention inevitably leads to water retention is compelling; however, were Na⁺ accumulation in part osmotically inactive, regulatory alternatives would be available. We speculated that in DOCA-salt rats Na⁺ accumulation is excessive relative to water. Forty female Sprague-Dawley rats were divided into four subgroups. Groups 1 and 2 (controls) received tap water or 1% saline (salt) for 5 wk. Groups 3 and 4 received subcutaneous DOCA pellets and tap water or salt. Na⁺, K⁺, and water were measured in skin, bone, muscle, and total body by desiccation and consecutive dry ashing. DOCA-salt led to total body Na⁺ excess (0.255 ± 0.022 vs. 0.170 ± 0.010 mmol/g dry wt; P < 0.001), whereas water retention was only moderate (0.685 ± 0.119 vs. 0.648 ± 0.130 ml/g wet wt; P < 0.001). Muscle Na⁺ retention (0.220 ± 0.029 vs. 0.145 ± 0.021 mmol/g dry wt; P < 0.01) in DOCA-salt was compensated by muscle K⁺ loss, indicating osmotically neutral Na⁺/K⁺ exchange. Skin Na⁺ retention (0.267 ± 0.049 vs. 0.152 ± 0.014 mmol/g dry wt; P < 0.001) in DOCA-salt rats was not balanced by K⁺ loss, indicating osmotically inactive skin Na⁺ storage. We conclude that DOCA-salt leads to tissue Na⁺ excess relative to water. The relative Na⁺ excess is achieved by two distinct mechanisms, namely, osmotically inactive Na⁺ storage and osmotically neutral Na⁺ retention balanced by K⁺ loss. This “internal Na⁺ escape” allows the maintenance of volume homeostasis despite increased total body Na⁺.