The behavior of rare earth elements (REE) in interaction between water and basalt was investigated on different conditions. The W-type tetrad effect was observed for water under gentle environment at room temperature. The REE pattern, having tetrad effect and negative Ce anomaly, is similar to that of seawater. On the other hand, the REE patterns of waters resulting from violent environment, i.e., at high temperature (70°C) or under operation of supersonic waves, show smooth curve with little if any tetrad effect, rather resembling that of source basalt. It is noted that the tetrad effect often observed in natural waters also appears in simple interaction in situ between pure distilled water and basalt. This results would throw light on understanding of tetrad effects observed in natural waters.