Sodium dodecyl sulfate (SDS) (purity, 99 %), NaOH (purity, 98 %), Na2CO3 (purity, 99 %), methylene chloride (purity, 99.9 %), MnSO4 (purity, 99 %), H2SO4 (purity, 98 %), KH2PO4 (purity, 99.5 %), HCl (purity, 37 %), K2Cr2O7 (purity, 99.9 %), potassium iodide (KI) (purity, 99 %), Na2S2O3 (purity, 98 %), Methylene blue (purity, 98.9 %) and ammonium molybdate (purity, 98.9 %) were procured for Loba Chemie Private Limited, India. All the chemicals were used without further purification. Redistilled and deionized water was used for solution preparation by dilution method. Nowadays, many of the cleaning of the cleaning detergents are available in the market. The composition and effect of DO were analysed from the selected laundry detergents such Sodium dodecyl sulfate (SDS) (purity, 99 %), NaOH (purity, 98 %), Na2CO3 (purity, 99 %), methylene chloride (purity, 99.9 %), MnSO4 (purity, 99 %), H2SO4 (purity, 98 %), KH2PO4 (purity, 99.5 %), HCl (purity, 37 %), K2Cr2O7 (purity, 99.9 %), potassium iodide (KI) (purity, 99 %), Na2S2O3 (purity, 98 %), Methylene blue (purity, 98.9 %) and ammonium molybdate (purity, 98.9 %) were procured for Loba Chemie Private Limited, India. All the chemicals were used without further purification. Redistilled and deionized water was used for solution preparation by dilution method. Nowadays, many of the cleaning of the cleaning detergents are available in the market. The composition and effect of DO were analysed from the selected laundry detergents such In present work, the content of surfactant in Keya, Rin, Chaka, Smart and Jet were determined at room temperature by MBAS colorimetric method employing UV-Vis spectrophotometer (Ibanez et al., 2008; Sar et al., 2009) where methylene chloride used as solvent and methylene blue used as organic dye. The absorbance was measured by spectrophotometer at 654 nm. It made sure that the spectrophotometer was previously calibrated using the methylene chloride so as to adjust the transmittance to 100%. The content of phosphates in selected laundry detergents were determined at room temperature by colorimetric method employing UV-Vis spectrophotometer (Ibanez et al., 2008), where stannous chloride, SnCl2 was used as a reducing agent. The absorbance was measured by spectrophotometer at a wavelength of 690 nm and it was adjusted to 100% transmittance with deionised water. Although surfactants and builders’ ingredients of laundry detergents play vital role for cleansing action, their extensive usages cause great risk for water environment, such as decreasing DO level, eutrophication effect (Ibanez et al., 2007) and so on. The effect of selected laundry detergents available in Bangladesh on DO level were determined by Winkler method (Winkler, 1888).