Water Hygiene

Water is the origin of the life of living organisms and is closely connected with human health. Water is the dissolved state of the compound (H2O). This compound is not found in its pure form in nature and contains various impurities. Water supply sources are divided into two forms: surface water and groundwater.

Drinking water is defined as water whose physical, chemical, biological, and radioactive properties are within a range such that consuming it for drinking does not cause any adverse effects in consumers in the short or long term. To ensure the safety of drinking water, its quality must be monitored at specified time intervals by conducting the relevant tests.

The sampling intervals for drinking and sanitary water are as follows: • Monitoring the chemical quality of water: once every 3 months • Monitoring the microbial quality of water: once every 15 days To learn about the physical, chemical, and microbiological parameters of water quality, one can refer to the standards "Drinking Water - Physical and Chemical Properties" and "Drinking Water - Microbiological Properties" from the Institute of Standards and Industrial Research of Iran, numbers 1053 and 1011 respectively. It should be noted that, given that correct sampling is of particular importance in reducing potential errors in water analysis results, sampling, transport to the laboratory, and water analysis must be carried out by specialists in accredited laboratories.

∴ Home water treatment devices The limited availability of fresh water sources on the one hand, and the urgent need of communities for water on the other, make the importance of water resource management a fundamental principle. One of the most common methods of water treatment, especially in areas where water sources of poor quality (high mineral content) exist, is the use of home water purifiers employing the reverse osmosis (RO) method. The ease of use and installation of RO devices in homes to achieve desirable water quality, as well as their simplicity and automatic operation and very small footprint, encourage water consumers to use these systems. Monitoring water quality before and after treatment by home water purifiers must be carried out regularly at the specified intervals as described above. Home water treatment devices can be installed under the kitchen sink or, in larger sizes, at the entry point of homes to treat all of the home's water. In these devices, water, after several stages of filtering, is pumped into a pressurized tank so that it can be used when needed. These devices are capable of removing more than 95 percent of substances insoluble in water and 99% of the living organisms and bacteria present in water. They also improve the taste of water by removing chlorine.

∴ Stages of the treatment process with a home RO system:

∴ The various parts of home water treatment devices

A home water purifier system generally consists of 5 filters, a water storage tank, and a pump to supply the inlet water pressure required by the system. In the first stage, there is the pre-filter (sediment filter), at which stage the removal of all suspended particles and sediments in the water (including sand and silt, iron particles from water transport pipes, algae, and other impurities larger than 5 microns) is achieved. The water then passes in turn through a granular activated carbon filter and a carbon block in order to remove contaminants such as chromium, mercury, pesticides, and chlorinated organic substances; chlorine, which shortens the membrane's lifespan, is also removed at this stage. In the next stage, there is the membrane filter, whose role is to remove a wide range of water impurities (including dissolved solids, bacteria, and viruses down to a diameter of 0.001 micron). After passing through the membrane stage, the water enters the storage tank. The activated carbon filter after the water storage tank is for improving the taste and flavor of the water before use. In the final stage of the system, a UV lamp is placed for water disinfection; the factors affecting the performance of the UV-ray disinfection system are the age of the lamp, the lamp's efficiency, and the sediment that forms on the lamp.

∴ When to replace the device's filters The time to replace the filters depends on the water quality, the plumbing network, and how much water we use. Replacing the first filter in home water treatment devices on time has a very large effect on extending the useful life of the other filters. The best time to replace the first filter (the sediment filter) is when the filter's color turns chocolate-brown.

• Activated carbon filter before the membrane: it is recommended to replace it every 3 to 6 months. • Membrane: it is recommended to replace it every 1 to 2 years. • Activated carbon filter after the membrane: it is recommended to replace it every 6 to 12 months.

∴ Limitations of using home water treatment devices:

1/ From the standpoint of health and environmental assessment

1/1 Washing RO filters requires sufficient knowledge of suitable solutions as well as the timing and method of using these solutions, but the majority of people lack the necessary expertise. Therefore, given citizens' lack of awareness about using suitable solutions to wash the filters, the lack of cost-effectiveness, and the lack of easy access, disposing of these filters into the environment is preferred. The annual disposal of large numbers of spent filters, without any special attention to its environmental consequences, along with municipal waste into the environment, entails substantial costs.

1 / 2 When the filters and membrane are replaced by individuals, there is a possibility of microbial contamination of the device, which causes the growth of a microbial mass and the formation of a biofilm on the inner wall of the device, and therefore the water coming out of the device will also be contaminated.

1/ 3 If these devices are not used for several consecutive days, the likelihood of microbial contamination of the water inside the device increases.

1 / 4 Research has shown that an average fluoride concentration of about 1 milligram per liter can be useful in preventing tooth decay. Studies have shown that the use of a home RO treatment system reduces the concentration of this element to zero.

1 / 5 The presence of residual chlorine in the municipal water distribution system, while controlling the growth of biofilm and planktonic bacteria, can also be a point of assurance in preventing secondary contamination. However, the removal of chlorine by the reverse osmosis system can, over time, provide an opportunity for biofilm growth and, subsequently, for opportunistic pathogens such as "Pseudomonas" and "Aeromonas."

1 / 6 Installing a UV lamp to disinfect the water coming out of the RO device is necessary; these lamps, depending on the type, have different useful lifespans, so it should be noted that if the lamp is not replaced on time or there is a delay in installing a new lamp, there is a possibility of microbial contamination of the outgoing water and, consequently, a threat to consumers' health.

1 / 7 Studies have shown that hard water is beneficial in preventing cardiovascular diseases, whereas in the reverse osmosis method, due to the high removal of divalent ions such as calcium and magnesium, which are the main constituents of water hardness, the final produced water ends up having very low hardness. It should be noted that water hardness should not exceed 350 milligrams per liter.

1 / 8 RO systems, by disrupting the ionic balance of water, reduce the pH of the water, such that this figure sometimes approaches the minimum permissible pH for drinking water. This, in addition to the water's lack of acceptance by consumers, will also indirectly play a role in the sanitary quality of the water.

2/ From the standpoint of economic assessment Reverse osmosis membranes, with low feed pressure and a high degree of salt removal, are considered an efficient option for water treatment; however, one of the factors limiting the use of these systems is high energy consumption.

Health recommendations

• If home water treatment devices are used continuously, replacing the device's filters on time and continuously monitoring the physical and chemical quality of the water coming out of the device, in accordance with the conditions stated, is recommended. • When replacing the filter of home water treatment devices, observing hygienic guidelines is necessary in order to prevent possible contamination of the filters. Contamination of the filters occurs upon contact with contaminated objects or hands. • Given the aforementioned health limitations, the water obtained from home water treatment devices should be consumed in a controlled manner, together with other sources, and with the approval of the relevant specialists. • If iron and rust problems are present, it is recommended to install a filter unit to remove iron before the reverse osmosis system.