The water uptake by the solid sorbents, carbon molecular sieves (CMS), graphitized carbons and polymeric sorbents, used to sample volatile organic compounds from air or water, was investigated by frontal chromatography. The humid air was passed through the sorbent bed and the uptake of water was monitored at the outlet of the trap. Graphitized carbons and non-polar polymeric adsorbents show poor water trapping of generally less than 5 mg per gram of adsorbent. Polar polymeric adsorbents adsorb more water which is, however, weakly bonded. CMS adsorb substantial amount of water, in the range ca. 200 to 450 mg per gram of adsorbent, however, these are considered to be non-polar adsorbents. The water sorption for graphitized carbons and polar polymeric adsorbents takes place only for very high relative humidity values (RH>~85%). For CMS an important feature is lack of water adsorption at low RH. Two different water adsorption mechanisms are operative: adsorption on polar centers and micropore volume filling. For graphitized carbons, polymeric adsorbents and CMS at low RH, adsorption on polar centers is involved. For CMS, once the threshold value of relative humidity (RH_th) is surpassed, micropore volume filling becomes predominant. RH_th depends on the CMS identity and are in the range 30 - 45% RH. The dry purging technique is suggested to remove adsorbed water. Graphitized carbons and polymeric adsorbents require only a few hundred milliliters of dry gas to remove adsorbed water entirely. Water can also be purged out from CMS; however much larger volumes of dry gas are needed. The water uptake can also be decreased using a novel but simple strategy for water management on CMS: moderate heating of the trap during sampling (a warm trap method).