Industrial wastewater, agricultural runoff, and sewage discharge are all major sources of water pollution. Industrial wastewater can contain toxic chemicals, while agricultural runoff can contain fertilizers and pesticides. Sewage discharge can contain harmful bacteria and viruses.

Water treatment is used to remove impurities, make water safe for drinking, and improve the taste of water. Impurities can include bacteria, viruses, chemicals, and sediment.

Filtration is a water treatment process that uses a filter to remove suspended solids from water. Suspended solids are particles that are small enough to remain suspended in water, such as dirt, sand, and algae.

Coagulation is the process of adding chemicals to water to cause impurities to clump together. This makes the impurities easier to remove by flocculation and sedimentation.

Reverse osmosis is a water treatment process that uses a semipermeable membrane to remove impurities from water. The membrane allows water molecules to pass through, but it blocks larger molecules, such as bacteria, viruses, and salts.

Agriculture is the land use that has the greatest impact on water quality. Agricultural activities, such as the use of fertilizers and pesticides, can lead to water pollution. Fertilizers can cause algal blooms, while pesticides can harm aquatic life.

Deforestation increases water pollution by reducing the amount of vegetation that can filter pollutants from water. Vegetation helps to remove pollutants from water by absorbing them through their roots and leaves.

Contour farming, terracing, and crop rotation are all land use practices that can help to reduce water pollution. Contour farming is a farming practice that involves planting crops along the contours of the land, rather than up and down slopes. This helps to reduce erosion and the transport of pollutants into water bodies. Terracing is a farming practice that involves building terraces on slopes to slow down the flow of water and reduce erosion. Crop rotation is a farming practice that involves rotating crops on a regular basis to help improve soil health and reduce the buildup of pests and diseases. All of these practices can help to reduce water pollution by reducing erosion and the transport of pollutants into water bodies.

Runoff is the process by which pollutants are transported from land to water bodies. Runoff occurs when water flows over the land and picks up pollutants, such as sediment, fertilizers, and pesticides. These pollutants can then be transported into water bodies, where they can harm aquatic life and pollute drinking water sources.

Deposition is the process by which pollutants are transported from the atmosphere to water bodies. Deposition can occur through wet deposition, such as rain or snow, or through dry deposition, such as dust or particles settling out of the air. Pollutants that are deposited on land can be washed into water bodies by runoff, where they can harm aquatic life and pollute drinking water sources.

Industrial wastewater discharge is a type of point source pollution. Point source pollution is pollution that comes from a single, identifiable source, such as a factory or a sewage treatment plant. Industrial wastewater discharge can contain a variety of pollutants, such as chemicals, heavy metals, and solvents.

Agricultural runoff is a type of nonpoint source pollution. Nonpoint source pollution is pollution that comes from a variety of sources, such as agricultural fields, construction sites, and parking lots. Agricultural runoff can contain a variety of pollutants, such as fertilizers, pesticides, and sediment.

Biodegradation, photodegradation, and volatilization are all processes by which pollutants are removed from water by natural processes. Biodegradation is the process by which microorganisms break down pollutants into harmless substances. Photodegradation is the process by which pollutants are broken down by sunlight. Volatilization is the process by which pollutants evaporate from water into the air.

Maximum contaminant level, secondary maximum contaminant level, and action level are all water quality standards. A maximum contaminant level is the highest level of a contaminant that is allowed in drinking water. A secondary maximum contaminant level is a non-enforceable guideline for the level of a contaminant that is considered to be aesthetically objectionable. An action level is the level of a contaminant at which water treatment is required.

Filtration is the process by which water is purified by passing it through a series of filters. Filters can remove a variety of contaminants from water, including sediment, bacteria, and viruses.