Raw water

[2] Farmers use it for watering their crops and give it to livestock to drink, storing it in man-made lakes or reservoirs for long periods of time.

Construction industries can use raw water for making cement or for damping down unsealed roads to prevent dust rising.

Raw water can also be used for flushing toilets and washing cars, as well as any other purposes that do not require it to be consumed by humans.

For example, endocrine disrupting chemicals can have harmful effects on fish populations living in natural lakes and rivers.

[12] Many contaminants, including iron, manganese, ammonium, traces of pesticides and medicines, organic micro pollutants, and radioactive particles can be removed with reverse osmosis alone.

Third, the water is slowly mixed in clarifiers where larger particles settle down to the bottom and are periodically removed (sedimentation).

[10] A disadvantage of this method is its use of chemicals, such as ozone, flocculents, hydrogen peroxide, lime, and chlorine for the filtration process.

Its advantages over conventional pre-treatment include: very high water quality independent of the contaminants in the initial raw water, a plant that is simpler in design and more flexible, which makes it easier to automate, lower use of chemicals, and final product free of viruses and microorganisms.

The biofilm membrane filtration method is used to remove harmful chemical by-products, such as NH4+-N, total nitrogen, and dissolved organic matter, that could form from disinfection processes.

[13] Biofilm Pre-treatment is a necessary step for water treatment in many parts of world due to its low operation cost and effectiveness at pollutant removal.

Even places with water filtration systems that meet standards can have an endemic of gastrointestinal illness, or waterborne infectious diseases.

[9] Controlling the land surrounding raw water reservoirs and other sources is key to reducing turbidity.

"Turbidity reduction is best achieved when the water is run through a series of chemical and physical treatment methods before reaching the filter".