The invention relates to a process for treating unwanted moderately saline waters for producing waters acceptable for treating soil, such as for irrigation. The treated water is also suitable for human and livestock consumption. The process includes passing moderately saline waters having 0.05% or more by weight and less than 1.00% by weight of the salts of Na, K, Ca, Mg, Fe, Cl, SO.sub.4, or CO.sub.3 or combinations thereof through an ion exchange resin. The ion exchange resin is pre-treated to be saturated with multivalent cations. Preferred multivalent cations include calcium (Ca.sup.2+) or magnesium (Mg.sup.2+) ions, or combinations thereof. After passing through the ion exchange resin, the effluent has decreased sodium cations and increased calcium and/or magnesium cations compared to the pre-treated moderately saline water. As the moderately saline waters passes through the ion exchange resin, the sodium content of the resin rises as the multivalent cation content lowers until the resin is unacceptable for further water treatment in accordance with the present invention. To regenerate the ion exchange resin, the resin is flushed with a brine solution having more than 1.00% by weight of the salts of Na, K, Ca, Mg, Fe, Cl, SO4, or CO3. Preferably, the brine is particularly high in calcium and/or magnesium content and low in sodium. The brine solution is flushed through the ion exchange resin until the ion exchange resin is sufficiently saturated with multivalent cations to again process moderately saline water having high sodium content.