Short answers, pulled from the story.
Water pollution is the addition of substances or energy forms that directly or indirectly alter the nature of the water body in such a manner that negatively affects its legitimate uses. This definition applies when contaminants mix with lakes, rivers, oceans, aquifers, reservoirs and groundwater.
About 4.5 billion people globally lacked safely managed sanitation as of 2017 according to UN data. Such conditions lead to open defecation practices where human feces move into surface waters during rain events or floods.
Some microorganisms sometimes found in contaminated surface waters include Burkholderia pseudomallei, Cryptosporidium parvum, Giardia lamblia, Salmonella, norovirus and other viruses. Indicator organisms such as total coliforms or fecal coliforms including Escherichia coli help investigate pathogenic pollution because detecting actual pathogens is difficult and costly due to low concentrations.
The U.S. Clean Water Act CWA defines point source for regulatory enforcement purposes amended in 1987 to include municipal storm sewer systems industrial storm water from construction sites. In Philippines Republic Act 9275 known as Philippine Clean Water Act of 2004 governs wastewater management stating policy to protect preserve revive quality fresh brackish marine waters.
Microplastics persist in environments at high levels particularly in aquatic and marine ecosystems where they cause water pollution with 35 percent of all ocean microplastics coming from textiles clothing primarily due to erosion of polyester acrylic or nylon-based clothing during washing processes.