In the paper, the measurement retention results concerning various categories of water (gravitational, available, unavailable, productive, easily available, difficulty available for plants) in selected points of an experimental field, destined to be intensively irrigated with the sewage water coming out of the urban sewage treatment plant in Lublin (the second degree of sewage effluent treatment) were presented. The area to be irrigated with the sewage water was situated in the Bystrzyca river valley, in the northwest part of the Nałęczów Plateau. Those soils where the experimental fields were arranged they represent the two subtypes of the post-bog soils, that is the peat-muck soil and mineral-muck soil. It was found out that the engineering works, which had been in the year 1996 carried out those did not essentially condense the soil material. A fact should be stressed here. Extremely strong, just drastically strong anthropogenic interaction, related to the works, which had been carried out there in the analysed area, did not destructive the natural retention properties of the investigated organic soils. No doubt the most favourable thin was the desiccation of the soil surface layer was of short duration, for the 1997 rainfall was exceptionally abundant. Moreover, irrigation was applied in zone "b". Where comparing the two soils, one should stress the favourable was the retention of the peat-muck soil, characterised by the higher contents of the organic substances and calcium carbonate than of the mineral-muck soil. Both soils show a similar retention property to the gravitation water and to the water unavailable for plants. On the other hand, the peat-muck soil can usually retain even two times more of available water.