We express our gratitude to the presence of Almighty God for the completion of the book Water Quality Engineering. This is an academic and practical contribution to the field of water resources management, with a focus on quality, sustainability, and the challenges faced in the modern era.

Water resource projects in human needs are increasing day by day in very high capacity. This is due to the increasing demand for basic human needs in supporting the quality of life through clean water projects. This is agriculture and other industries are very unavoidable due to the factor of water
availability in long-term capacity must be ensured in every 5 ,10 years in the future, water sufficiency in ensuring the feasibility or quality of water is guaranteed. from the many backgrounds of interpretation about water quality, for example, water resources form liquids that are really needed by our other bodies, then the second factor of water quality that contains the concentration of living things, energy, substances or concentration of solutions in the water in it, including a decrease in water levels that have not changed the designation of raw water and water quality, this is caused by the entry of substances into water or humans so that the quality of the water decreases causing the water to no longer be suitable for its purpose, one of which is the level of water pH is still higher between the limits of lime content, energy substances, other components can change the concentration of substances, both chemical substances into toxic substances that contain negative ions so that their presence in water in certain water sources according to their designation, including the burden of water pollution that damages the number of levels of water quality parameters or liquid waste contained
in it, a mixture of colored substances and a foul odor is definitely not suitable for use or utilization, the occurrence of itching or a decline in public health if using water that is not suitable for consumption.