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| Food Standards |
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| To prevent adulteration and to maintain availability of good quality food stuff, the government has set up certain institutions for standardization. They are: |
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 Codex Alimentarius |
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 Prevention of Food Adulteration Act (PFA) |
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 The Agmark Standards |
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 Bureau of Indian Standards (BIS) |
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| These institutions inspect the food processing factories and food products manufactured. If the products satisfy all the required conditions, certificates using the FPO mark, Agmark or ISI marks are awarded. These marks can be used on the products which denote that the food is reliable. Any food product that does not satisfy the minimum standards of quality and purity are liable for prosecution and punishment under the law. |
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| Rain is the main source of water. A part of the rain water seeps into the ground, to form ground water, some of it evaporates back into the atmosphere and some of it flows to form streams and rivers which flow ultimately into the sea. In rural areas open wells and bore wells are the main source of water supply. Urban areas rely on river water for their needs. River water has to be purified before it is supplied for public consumption. If water is not purified, several water-borne diseases like cholera, diarrhoea and hepatitis can break out in the form of epidemics. The methods adopted by the waterworks department to purify water are physical, chemical and microbiological. Purification of water is implemented in three steps i) storage ii) filtration iii) disinfection. |
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 Storage |
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| By the process of storage about 90% of the suspended impurities settle down and form a sediment within 24 hours. The supernatent clear water is then taken for further purification. |
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 Filtration |
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| Floating impurities and about 98-99% of bacteria are removed by filtration. |
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 Disinfection |
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| The filtered water is disinfected by the process of chlorination, ozonation and ultraviolet irradiation. Chlorine kills pathogenic bacteria but has no effect on spores and viruses that cause diseases like polio, viral hepatitis and jaundice. Ozone eliminates undesirable odour, taste and colour and removes the chlorine from water. It also has a strong virucidal effect and inactivates viruses. |
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| To ensure that the water that is supplied to the home is totally safe for the purpose of drinking, the following methods of purification should be adopted. |
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| i) Boiling ii) Storage iii) Filtration iv) Disinfection |
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| Boiling water kills germs and viruses and makes it safe for drinking. It must be ensured that the water is boiled for 3-5 minutes. |
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| In rural areas, water is stored in large copper vessels and earthen pots. When water is stored in copper vessels, the copper ions will reduce the bacterial flora in the water, thereby purifying it. Bacterial flora also gets reduced when water is stored in porous clay vessels. If camphor is added to the water the microbial population gets reduced due to the oxygenated monoterpenes. The addition of tulsi (ocimum) leaves to the water has a similar effect on the microorganisms because of the eugenol content. |
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| The following techniques are adopted for purifying water in homes. |
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| a) Candle Filter: Several brands of water filters are available in the market which utilize the candle technology. The filter consists of two containers fitted one above the other. Fixed in the centre of the upper container is a ceramic candle. The water to be purified is poured into the upper compartment. The ceramic candle acts like a filter and removes fine impurities and bacteria. The filtered water collects in the lower compartment. Care should be taken to keep the candle clean. It should be scrubbed well with a brush, washed thoroughly and then boiled. |
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| If a small amount of alum is put into the water, dissolved impurities will precipitate out. |
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| b) Sand filter: Water is purified in villages using this technology. Water is passed through different containers containing sand, gravel and charcoal. Purified water is collected in the bottommost vessel. |
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| Water filter in rural homes |
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| In urban areas the same technology and can be modified and used in over head tanks. |
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| Water filter in urban homes |
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| c) Compact integrated electronic device: These are water filters very popularly used in homes and hotels. This filter operates with the help of electricity. The device uses a porcelain filter, charcoal and UV rays to purify the water. |
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| d) Membrane technology: This is the latest technology which uses the principle of osmosis. It does not require electricity and maintenance is minimum. The water obtained through membrane technology is very pure and without any contamination. This type of filter is widely used in homes , hospitals and hotels. |
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| Chemical disinfection is brought about with the use of chemical disinfectants such as bleaching powder, chlorine solution, ethanol solution of iodine and potassium permanganate. Chlorine tablets are available at cheap rates to disinfect water. A single tablet of 0.5g is sufficient to disinfect 20 litres of water in one hour. |
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| Double pot |
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| Wells can be disinfected using the double pot method. A mixture of bleaching power and sand is used. This method ensures a constant dose of chorine to well water for its disinfection. The double pot method is particularly adopted on a mass scale when there is an epidemic of cholera, gastroenteritis, hepatitis, typhoid etc. The quality of drinking water has to be maintained to prevent the breakout of these diseases. |
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Boiling
Storage 
Filtration
