Summary The water quality effects on swelling ( S ), effective mean pore radius ( r ), water penetrability ( λ ), and weighted-mean diffusivity ( D ) in loamy sand soil columns treated with 0.4% of three gel-conditioners (StaWet, Superhydro, and Hydrogel) were studied. Four waters: salt solution (SS, EC = 42.5 dSm −1 ), distilled (DW), sewage (SW, EC = 1.6 dSm −1 ), and well (WW, EC = 6.4 dSm −1 ) waters were used. For the three gel-conditioned soils, S decreased with increase in water salinity. A critical EC of 6.4 dSm −1 was suggested. In general, S of gel-conditioned soils ranked as follows: Super hydro > StaWet = Hydrogel. However, the sensitivity of the gel-conditioner to water salinity is directly related to its swelling capacity. The results indicate that Hydrogel reduced λ to sufficient level with irrigation water up to 6.4 dSm −1 , while superhydro and Jalma reduced λ to sufficient level with irrigation water of salinity level of 1.6 dSm −1 . The 0.4% StaWet was not enough to reduce λ to sufficient level even with distilled water. Effective pore radius was a very reliable predictor of the multiple effects of texture, gel-conditioners, application rates, and water salinity on λ and D . Weighted-mean diffusivity may be predicted from knowledge of λ .