Water quality assessment of open wells in Malappuram district, Kerala, India

Water is one of the most precious commodities in this world. Although two-thirds of Earth's surface is covered by water, only a small amount of water can be effectively utilized for human needs. Surface sources contribute about one third of the drinking water requirements of the world. Unfortunately, this small amount of potable water is also deteriorating day by day due to anthropogenic activities. The problem has been intensified in the last few decades and the situation is alarming in most places.

Kerala is known as God's own country because of its abundant natural resources, mainly water. The state usually receives a tremendous amount of rain water, about 2,800–3,200 mm of rain every year. There are 44 rivers and 34 backwaters; mostly in the form of lakes and ocean inlets and others are fresh water lakes. Besides this, the state is blessed with numerous streams, about 18,600 ponds and over 70 lakhs dug wells. Kerala is one of the most dug well density areas in the world (Harikumar & Kokkal 2009; Geethu Krishna et al. 2014).

In the modern world, water pollution is one of the most serious problems. Like most of the other types of pollution, water pollution is also associated with human activities. Human and animal feces, seepage from pit latrines and septic tanks, household waste, refuge dumps, industrial, domestic, and all municipal wastes released into water bodies, agricultural runoff, landfills debris from, construction sites, etc. are some of the important causes of water pollution. Pollutants may be decaying and miscible with soil and waterbodies. An obvious and asymptomatic issue with the pollutants is their effect on water quality. Decomposition of the above pollutants may result in the production of compounds like carbon dioxide, water, simple organic compounds like methane, simple fatty acids, etc. (Dlugokencky et al. 2003). These substances may be miscible with rain water, oozing through the soil and reaching the ground water as well as deep ground water which causes the contamination of ground water sources, too.

Most of the land area in Malappuram is thickly populated and hence the place has a high pollution rate where water is one of the most evident victims of pollution. In Kerala, the southernmost state of India, most of the people depend on the open wells or shallow wells and each house has at least one well. The sources are most often surrounded by so many pits like soak pits, leach pits, pit latrines, septic tanks, etc. As the contaminated water may be leaching from the pits, these pits increase the chances of contamination.

In the rainy season, there is an excess quantity of water in all sources and hence less chemical quality problems are found. Although the Bureau of Indian Standards (BIS) has fixed the quality standards for drinking water, most of the drinking water sources are below the standards due to excess pollution (Bureau of Indian Standards 2012). In this regard, the present work aimed at assessing various water quality parameters of open wells in Malappuram district, Kerala. The study was carried out in the month of January 2022 which is in between the post-monsoon and pre-monsoon seasons in Kerala.

For the analysis, analytical grade chemicals and doubly distilled water were used. The water quality parameters were analyzed as per American Public Health Association (APHA) (APHA 2005) and the quality parameters were followed as per BIS 10500:2012 (Bureau of Indian Standards 2012). The instruments such as a thermometer, portable pH meter, nephelo turbidity meter, and UV-visible spectrophotometer were used in the analysis. Forty-five samples from open wells were collected randomly from 15 blocks (three samples from each block) in the Malappuram district. Samples were collected in a clean and fresh 1 L plastic cane. The physical parameters like temperature and pH were analyzed at the time of sampling itself whereas turbidity total dissolved solids (TDS), acidity, total alkalinity, and iron were analyzed in the water testing laboratory.

To analyse the water quality, samples were collected from open wells of 15 blocks in Malappuram district, Kerala, India, during the period between post- and pre-monsoon seasons. The study reveals that all the 45 samples have low pH and the water in these open wells is slightly acidic. The turbidity of 13 samples is found to exceed the permissible limit. Dissolved solids and total alkalinity in all the samples are within the desirable limit. The hardness and presence of chloride are very low in the open well water samples of the Malappuram district. As nine samples show excess iron contamination, these samples are not fit for drinking purposes as per BIS and hence proper treatment methods should be adopted before the use of this water.

All relevant data are included in the paper.

The authors declare there is no conflict.