Urban and suburban water is more difficult to find when it does not come out of a tap. Tap water is treated and usually safe, as long as the treatment plant is operating properly. However, during a disaster like a hurricane, tornado, earthquake, or terrorist attack, the water supply will become unusable.

If it becomes necessary to find water in the city or neighborhood, you can look for ponds, swimming pools, fountains or canals and ditches. It is usually much more difficult to find water in developed areas because most houses and apartment buildings are not located near bodies of water.

Even if your home is located near water, you still have to find a way to collect enough for the family and transport it from its source to the house. At roughly 9lbs per gallon, it requires a lot of physical strength to carry even a small bucket of water.

Even if you do live near water, there is another problem. Untreated water can have many of the same pollutants and toxins as wild water, plus many more. Urban water is almost always contaminated with a variety of runoff pollutants ranging from fertilizers to heavy metals.

Here’s a list of typical urban water runoff contaminants:

• Engine oils
• Rubber from vehicle tires
• Heavy metals from vehicle engines, machinery and roof shingles
• Fecal bacteria from pets and poorly treated sewage
• Fertilizer chemicals that include phosphorus, nitrates and others
• Pesticides
• Herbicides
• Cleaning solution chemicals
• Runoff from garbage dumps
• Spilled or washed off chemicals from paints or stains
• Pollutants deposited from the air like nitrates, ammonium and acid rain
• Bacteria
• Viruses
• Insect eggs, larva and remains
• Volatile organic materials
• Salt from road maintenance materials
• Chemicals from industrial runoff
• Other chemical compounds like polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs)
• Decomposing plastics materials
• Sediment

It seems that road runoff, commercial, residential and air pollutants can contain just about anything, making urban water dangerous to drink. You would think that so many pollutants would be easy to see in the water, but most of them are quite small and invisible to the naked eye.

For example, bacteria averages 2-5 microns in size, while viruses are as small as .004 microns. The parasite giardia lamblia averages 8 to 12 microns, while cryptosporidium parvum is 4-6 microns. The incredibly small size of some water pollutants means that you must be careful when choosing the method of water purification. The purification process used has to effectively remove or make harmless the most common urban water contaminants.