| Wastewater is water that has come into contact with | | | | unfit for drinking and one gram of a common |
| any of a variety of contaminants and is not fit for | | | | household herbicide can make ten million liters of water |
| human consumption. Most often, wastewater has its | | | | unfit for drinking. Only one gram of PCB can |
| source in domestic settings, commercial operations, | | | | contaminate one billion liters of water, making it unfit for |
| industry and agriculture. Groundwater becomes | | | | aquatic life. One gram of lead in 20,000 liters of water |
| contaminated from many sources. "Point" sources | | | | renders it unfit for drinking. |
| include municipal landfills, leaking gasoline storage tanks, | | | | Oil and gas drilling is a worrisome source of |
| leaking septic tanks, accidental spills and industrial | | | | wastewater, as more attempts are proceeding to find |
| waste disposal sites. "Non-point" sources include runoff | | | | local sources of these fuels. The contaminants |
| and seepage from agricultural lands containing | | | | resulting from these operations contain cadmium and |
| pesticides and fertilizers. | | | | benzene, both carcinogenic elements. They are |
| Blackwater refers to wastewater that contains human | | | | released into the massive amounts of water injected |
| waste, usually from lavatories. This also becomes | | | | under pressure to force gas out of the ground. A |
| sewage, when it empties into a municipal sewage | | | | more dangerous contaminant resulting from drilling is |
| system. Greywater is that water that contains | | | | the grit, called Totally Dissolved Solids (TDS) that are |
| contaminants from washing; laundry, bath, shower, | | | | dredged from deep underground. TDS contains |
| dishes. Stormwater is the runoff after a rainstorm, and | | | | minerals and salts in such concentrations that the |
| most often runs into a municipal sewage system. | | | | wastewater resulting from contamination by TDS is |
| Otherwise, it flows into creeks, rivers and oceans. | | | | five times as salty as seawater. It alters the taste of |
| Domestic- source wastewater contains food, cooking | | | | groundwater, but more dangerously clogs rivers and |
| oils, drinks, pesticides, paint, cleaning fluids, rainfall from | | | | streams and affects the health of those waters. With |
| roofs, which contain oils, fuels and litter. Wastewater | | | | increased drilling, the bio-systems are becoming |
| from roads also is contaminated from fuels, salt, rubber | | | | overwhelmed in their capacity to neutralize these |
| residue, animal excrement and litter. Industrial sources | | | | contaminants. |
| of wastewater contain contaminants including oils, | | | | Wastewater is primarily treated at municipal water |
| chemical residues, pharmaceuticals, pesticides, silt, | | | | treatment plants in North America. These plants |
| cooling compounds, metal plating, and a variety of | | | | separate solid and liquid waste. The liquids are typically |
| other by-products of manufacturing processes. | | | | sent off to further filtering and treatment by bacteria |
| Water that has been used for cooling in a | | | | and chlorine, while the solid wastes are often treated |
| manufacturing process becomes wastewater after if | | | | with micro-organisms that are able to break down the |
| has warmed. Other industrial processes require | | | | sludge and absorb and neutralize contaminants. Septic |
| de-ionized water. When this water has been used in | | | | systems use gravel, sand or reed beds to hold and |
| that process, it becomes wastewater. | | | | filter the liquids, while the solids are contained and |
| One drop of oil can make twenty-five liters of water | | | | physically removed when the tank is full. |