Water contamination is a serious form of pollution, and one that can be challenging to rectify. There seem to be two main causes involved, and a variety of damaging effects on people and the biosphere, which we will discuss here.
Probably the main factor is the issue of emissions from cars, factories and other human activities. These emissions contain damaging pollutant particles which can contaminate rainwater run-off and thus enter the water cycle, by transferring through the water table into aquifers, streams and rivers. Filtration and processing are not really viable options for such large volumes of water, and so the water table remains tainted with these elements over long periods, as we see in Eastern Europe today. In situations where soil erosion and logging have already damaged the local environment, the accumulation can be very serious. The other major cause is accidental or deliberate dumping of waste products in places outside of controlled landfills or waste processing centres. Even small amounts of abandoned waste can enter water supplies through the ground, often undetected.
The effects on animal life can be severe, especially for species which are already endangered by such threats as poaching, habitat loss and food chain disruption. Contaminated water can lead to dwindling numbers or even potential extinction, as may indeed happen to the Asian tiger populations. The impact on human society can also be distressing, including the poisoning of drinking water, famine or drought due to lack of safe irrigation, and long-term loss of land as we see, for example, after the Bhopal poisoning catastrophe in India. Such effects tend to have an especially grave impact on the very poorest in society, with the least resources to counter the environmental effects.
Overall, we see that emissions and dumping are the main origins of the problem, and that the effects on both humans and animals are exacerbated by the existing environmental, criminal or social problems.