What is safe drinking water?

In theory, the process from the plant's treated water source to the user's hand must meet strict safety standards and must not contain any hazardous substances that pose a health risk. However, in reality, abnormalities in clean water can still occur due to problematic water treatment processes, as in the recent Hanoi clean water pollution incident. The most concerned issue right now is how to recognize safe drinking water and how to handle it when clean water is contaminated.

Water can be contaminated in many ways, including:
Contains microorganisms such as bacteria and parasites that get in from human and animal feces; Chemical contamination from industrial waste or from pesticides, chemical fertilizers when farming (nitrates used in fertilizers can leach into the water through runoff from the soil); Various minerals such as lead or mercury can enter the water supply from natural deposits underground, or from improper disposal of pollutants. Chemicals that pollute clean water can affect everyone's health, but the effects will be more severe for some of the following:
People who have undergone chemotherapy; HIV-infected people; Organ transplant patients; Children and infants; Pregnant women and fetuses;

Tap water when reaching the user must ensure strict safety standards. Pollutants are still possible, but usually do not pose any serious health risks. However, there are still cases where the water source is not treated thoroughly, leading to toxic residues in the water, such as the recent Hanoi clean water incident.
Contamination of clean water can be caused by contamination from upstream that cannot be cleaned up by the factory process, broken water pipes, or lead from pipes seeping into the water - this is quite a serious problem Because even though pipes are labeled "lead-free," they can still contain 8% lead in their composition.
The best way to avoid absorbing lead in tap water is to let it drain for about 1 minute before using it. If used for eating and drinking purposes, only take water from cold faucets, do not use warm/hot faucets because high temperatures can cause lead to seep into the water more.

Today, well water is still widely used in people's daily life. The quality and safety of well water depends on the following factors:
Construction structure of the well; Location of wells; The quality of the aquifer supplied to the well; Works around the area where the well is located; How to maintain water source for wells. These factors should be discussed carefully with a professional before deciding to build a well. Besides, in the process of using well water, it is necessary to check the water quality and well structure regularly, as soon as abnormality is detected, the cause must be found out and resolved soon.

Bottled water is often considered safe for health, when it is subject to strict regulations on water sources, permissible levels of chemicals, microorganisms, and radiation; standards of practice and labeling regulations,...
In reality, however, about 25% of bottled water is simply purified tap water. So how to know if bottled water is really natural mineral water or just a product of a water purifier? Look on the bottle label, if it says “ground water” it is natural mineral water, while the rest only say “pure water” or “distilled”.

The effects of contaminated water on human health depend on the type of contaminant. Example:
Cryptosporidium : A protozoan parasite of the phylum Apicomplexa that sometimes occurs in water supplies. It causes gastrointestinal diseases (mainly diarrhea ) and is potentially fatal; Nitrates : Possibly an immediate threat to infant health. In the intestines, nitrates are converted to nitrites, which prevent the blood from carrying oxygen; Lead: Causes physical and mental development problems in infants and young children. Adults who drink lead-contaminated water for many years can develop kidney disease or high blood pressure.

In the context of polluted clean water, many people will tend to switch to water purifiers in an effort to find a safe source of drinking water for themselves and their families. Here are 4 types of working mechanisms of 4 types of water purifiers you can refer to to choose the right one for your needs:
Use an activated carbon filter: Helps remove some organic pollutants photo affect the taste and smell of water. Some machines are also designed to remove chlorinated byproducts, solvents (a chemical that is very dangerous if swallowed and enters the respiratory tract), pesticides or metals such as copper and lead; Using ion exchange technology: With activated alumina, it can remove minerals such as calcium and magnesium, forming "hard water". This method is often used in conjunction with other filtration methods, such as carbon adsorption or reverse osmosis; Using reverse osmosis technology: Can remove nitrate, sodium, pesticides or petrochemical products; Using distillation technology: Boil water and condense steam to produce distilled water; However, we need to know that, no water filtration system can remove all harmful substances at the same time. Therefore, you should find out the nature of your home's water source (by sending samples to the laboratory) to determine what harmful substances are present in the water that need to be removed, then choose a water purifier with suitable feature.
Besides, it is necessary to pay attention to cleaning the filter regularly and properly, because over time harmful substances will accumulate in the filter, making the quality of water after filtration even worse than before. filter.

According to the Guidelines on Drinking Water Quality provided by the US National Center for Biotechnology Information (NCBI), assessing whether drinking water is safe or not can be based on the following factors: microorganisms , chemical, radiological and sensory.

Humans pose health risks when consuming drinking water containing human and animal excreta.
Microorganisms in water capable of causing disease include:
Bacteria, viruses, protozoa and helminths; Potential pathogens, such as Helicobacter pylori, Tsukamurella, Isospora belli and microsporidia, for which waterborne transmission is plausible but unconfirmed; Cyanobacteria. Among them, infectious diseases caused by bacteria, viruses and parasites are the most common health effects associated with drinking water. Specifically, these agents include:
Bacteria: Burkholderia, Campylobacter, Escherichia coli, E.coli, Shigella,.... Virus: Adenoviridae, Caliciviridae, Hepatitis E Virus, Enteroviruses, Rotavirus Virus,... Animals protozoa: Acanthamoeba, Cyclospora, Entamoeba,... Worms: Dracunculus. Certain pathogens transmitted by contaminated clean water can lead to serious, life-threatening illnesses such as typhoid, cholera, infectious hepatitis (caused by hepatitis A or E viruses), bacterial dysentery Shigella bacteria, and some other illnesses that are usually less serious, such as self-limited diarrhea.
The effects of pathogens in humans are not the same for all populations. Vulnerable groups - including children, the elderly, pregnant women and people with weakened immune systems - will have a higher probability of getting the disease and its severity. Contaminated water can also be the source of disease outbreaks, for example cholera, dysentery...

As mentioned, the majority of health problems associated with drinking water are caused by microorganisms. However, a significant number of cases of serious health damage are caused by chemical contamination in drinking water.
Exposure to toxic chemicals in drinking water usually does not cause immediate health effects, so it is difficult to identify a problem water source for timely intervention. At this time, the role of inspection and supervision is extremely important.
Some typical chemical contaminants of drinking water include: Styrene, aluminum, ammonia, arsenic, benzene, acetic acid, chlorine hydrate, chloride, chlorine, chromium, copper, lead, mercury,...

Drinking water may contain radioactive substances that are dangerous to human health. These risks are usually smaller than those posed by microorganisms and chemicals in drinking water. Except in extreme cases, the radiation dose resulting from the ingestion of radionuclides in drinking water is much lower than that obtained from other sources. Clean water when contaminated may contain radionuclides of natural or man-made origin:
Natural radionuclides: Includes potassium-40, radium-226, radium-228, uranium-234, uranium-238,... found in water either by natural absorption (e.g. from soil), or by manufacturing processes involving naturally occurring radioactive substances such as mining and ore processing ,... Artificial radionuclides: Due to discharge from nuclear fuel production facilities, or due to residual radiation from the past released into the environment. Any radiation exposure carries risks. For the case of drinking contaminated water for a long time, there is evidence of an increased risk of cancer.

When assessing the quality of clean water, users mostly rely on sensory perception. Sensory factors include color, odor and taste. Clean water should not have odors and tastes that are offensive to most users. The color, smell and taste of water can change as a result of organic and inorganic chemical contamination, biodegradation, corrosion, or as a result of water treatment (chlorine odor). In addition, clean water with a strange taste and odor can also indicate a problem with water treatment or distribution.
The color, odor and taste of water are changed by the following agents: Contaminants of biological origin, including: Actinomycetes and fungi: Causes unpleasant odors and tastes when drinking; Cyanobacteria and algae: Make the water cloudy; Visible invertebrates (eg snails, worms, water lice,...) and microscopic species; Iron bacteria: An organism that, when combined with iron (manganese) and oxygen in water, will create rust deposits on the walls of tanks, pipes and sediment in the water. Chemical contaminants include: Aluminum: Discoloration of water or deposits; Ammonia: Causes pungent odor; Chloramines: Affects the smell and taste of water; Chloride: High concentrations cause a salty taste to drinking water; Chlorine: Causes a pungent odor; Chlorobenzenes: Changes in odor and taste; Chlorophenol: Very mild odor and taste change; Copper: High concentrations cause discoloration and bitter taste in water; Ethylbenzene: Fragrance; Water hardness: Hard water often causes scale in the kettle, making soap less foamy,... Hydrogen sulfide: Smells of rotten eggs; Manganese: Causes unpleasant odors and tastes in drinking water, stains clothes; create a black residue film in the pipeline; Styren: Causes mild sweetness. Zinc: At concentrations in excess of 3 FPV5 mg/l, water turns milky white and creates a scum on the surface of the water when boiled. About color: Safe drinking water must be colorless. The color of water is often due to the presence of colored organic substances (mainly humic and fulvic acids) in the soil, due to the presence of iron and other metals. It can also be the result of water pollution by industrial wastewater, which is a very serious phenomenon. Most of us can detect the color of water with the naked eye at levels above 15 TCU (units). color), while water with a TCU level below 15 is generally still acceptable to users.
About turbidity: Turbidity of water is measured in NTU (Nephelometric Turbidity Units), caused by suspended particles (such as clay, sand), chemical precipitation, organic debris and organisms. Below 4 NTU, turbidity can only be detected by specialized instruments; from 4 NTU or more can see turbid water such as milky white, mud color, reddish brown or black. Clean water will be cloudy if the upstream water quality is poor, water treatment is not good or distribution process is not guaranteed, the ingress of dirty water in the place of broken pipes,... High turbidity of the water causes discoloration of clothes,...
How to handle when the water has strange color, smell and taste? Sensory problems with water will be solved by conventional cleaning methods such as deposition or chlorination. In cases where intensive treatment is required, aeration, granular or powdered activated carbon, and ozonation can be used to remove organic and inorganic chemicals quite effectively. Specifically, manganese in water can be removed. removed by dechlorination and then passed through the filter; remove hydrogen sulfide by aeration, activated carbon and oxidation; removal of ammonia by biological nitrification; Reduces water hardness by softening precipitates and cations. Other odor and taste altering inorganic substances such as chlorides and sulfates are usually irreversible.

Reference source: webmd.com, NCBI