Rats, flies and mosquitoes abound at contaminated water sources and inadequate sanitation facilities, and typhus, dysentery and encephalitis become the scourges of the poor. Low levels of health care and education and, above all, poor personal hygiene and nutrition compound the problem. Safe water is critical but, too often, municipal governments assume that the poor can't afford water and sewer lines. Ironically, poor families already pay a large portion of household expenses for water, but they're paying private water vendors. Urban families would in fact pay the city to bring them safe drinking water and remove waste water.
Safe water can also positively affect indoor air.
If slum dwellers don't have to boil their drinking water, they burn fewer fires and produce less soot and smoke. Their lungs and their water are cleaner, and so is the city's air. Another severe health threat is particulate air pollutiondust and soot from vehicle exhaust, industry, power plants, space heating, construction, cooking and trash burning. This is proving to be far more damaging to human health than once believed. Fortunately, it's also manageable.