Today, the reuse of waste in building materials occupies an important place in the approach to the circularity of materials. National and European environmental regulations require ensuring the environmental safety of material-incorporating waste. For this, there are specific tests to verify that there is no health risk when using these materials. Concretely, to check the environmental acceptability of construction materials, including wastes, the release of hazardous substances into water must be assessed. In this research, we performed a diffusion test with the sequential renewal of water during a 64-day period according to the NF EN 15863 specifications on polymer mortar monoliths, common construction products used in floor-covering applications and incorporating sediments. Polymer mortars were prepared at a laboratory scale by incorporating 30 or 50% of polluted sediment for various polymer concentrations (12, 14, 16, 18, 20 and 25%). It was shown that the release of inorganic substances is limited in these hydrodynamic conditions. Among trace elements, As, Cd, Cr, Ni, Pb and Zn are lower than quantification limits in most leachates, whereas Ba, Co, Cu and V are systematically quantified at low concentration levels. This is particularly true for samples displaying the highest polymer concentration (25%) and the lowest sediment incorporation rate (30%). This is because of the low water absorption level and low porosity of polymer mortar matrices. No adverse effect is to be expected for environmental health from the leachates of these construction materials, including waterways sediments, because all the measured parameters were below the Soil Quality Decree limits applied in the Netherlands for environmental assessment of construction products.