Well Water Chlorination

Water Wells are the prime source of water in the rural areas of India. Every house in rural India has a well in their premises meeting all the water demands of its inhabitants. The very first thing that a common man will look for before constructing a house is the availability of a perennial source of  good quality   water table so that he can dig a well in his backyard.Well water is usually rich in minerals compared to the surface water sources and often water treatment is required before drinking it. There are houses where people drink the well water directly without even boiling it. But, is just boiling the water sufficient to disinfect it? Every well varies in its depth, volume and quality. Well water contamination  usually occurs from our own carelessness. But there are some easy methods of disinfecting and treating the water in the well making it potable and we will be learning  one of the best  methods in today’s article.

Why Disinfect Well Water?

Well water is easily contaminated from the nearby septic tanks, garbage pits. If the wells are not properly maintained, the water becomes infected with various pathogens . E Coli contamination are very common in such well water. In urban areas adequate safe distance between water well and septic tanks are often not maintained. If the wells are not sealed properly bird droppings, animal waste can also become sources of contamination. Many water-borne diseases like Typhoid, Cholera, Diarrhoeal diseases, Dysentery, Hepatitis etc can be prevented by treating the water and making it safe to drink. In areas of epidemics, the disinfection process has to be done at frequent intervals.

Bleaching Powder Disinfection

The easiest, cheapest and the most effective method of disinfecting well water is to use Bleaching Powder. The basic principle behind using Bleaching powder is to use the Chlorine content in it which is a very effective water disinfectant. Bleaching powder is chemically chlorinated lime with the chemical formula , CaOCl₂. The main aim of the chlorination process is to ensure a free residual chlorine of 0.5 mg/litre at the end of one hour of contact period.. Before determining the amount of Bleaching owner required for chlorination, we have to measure the volume of the well to be disinfected.

How to find the Well Water Volume?

Let “h” be the height of water column in the well. We have to measure it several times and take the average value. If you have any difficulty in this regard, try to contact the person who drilled the well.

Let “r” be the radius of the well. We should first measure the diameter of the well and then derive its radius by dividing the value by 2.

Volume = 3.14 x r² x h x 1000

Assuming that the height and radius were measured in “metres”, the volume can be derived in litres using the above formula.

Finding the amount of Bleaching Powder

About 2.5 grams of Bleaching powder would be required to disinfect 1000 litres of water. In order to measure the quantity of bleaching powder required accurately, one must use the Horrock’s apparatus which measures the actual chlorine demand of water.

How to make Chlorine Solution?

The required amount of bleaching powder measured in the above step is taken in a bucket and is mixed with water. A thin paste is first made and then additional water is poured into the bucket till it fills three-fourths of the bucket. The contents are stirred well and then allowed it to settle for about 15 minutes. The supernatant , which is the actual chlorine solution to be  used is transferred to another bucket . The deposited lime in the first bucket should be discarded.

The Chlorination Process

The chlorine solution prepared in the previous step is introduced into the well in a bucket  below the water surface. The chlorine solution in the bucket has to mixed with the well water by violently agitating the bucket  by moving it upwards, downwards and sideways several times.Water in the well may be used after one hour of the mixing process.

The chlorination process should be carried out every 6 months. During epidemics of Cholera, the frequency of chlorination may be increased.

Some other basic steps to be followed in order to guarantee a safe source of drinking water are lining the well, sealing the well head, keeping the area clean and free from stagnant water and  ensuring adequate distance from septic tanks and garbage pit.

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