The paper presents the results of investigations into the efficiency of treatment of the waste rainwater drained from the Lublin Agricultural-and-Horticultural Market in Elizówka. The assessment of the treatment efficiency was carried out on the basis of four series of measurements made in different seasons of the year. The sewage samples were taken from two storage reservoirs. The following physicochemical properties of waste rainwater were determined: pH, temperature, conductivity, suspended matter, dissolved oxygen, BOD₅, COD_Cr, N-NH₄, N-NO₃, N-NO₂, PO₄, SO₄, K, Cl and Fe. In the sewage from reservoir No 1 (tight clarifier) the admissible values were exceeded several times; this referred particularly to the levels of suspended matter and conductivity. In the sewage from reservoir No 2, in which there is infiltration into the ground, all components, apart from pH which showed excessive values, were in the standard range. The values of the majority of indicators remained on a similar, normative level. The concentration of chlorides increased after snowmelt runoffs, but even at that time it did not exceed the admissible value. A considerable decrease in the quantity of most impurities after the passage of water from the clarifier to the retention-and-infiltration reservoir indicates that the treatment plant functions properly.

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