Safe Water & Treatment of

Drinking Water Notes

• Water Treatment Process– Sedimentation – the heavy particles settle to the bottom and the clear water

moves on.– 1st Filtration – the water passes through a layer of sand to remove large

particles.– Coagulation- removes dirt and other particles suspended in water. Alum

and other chemicals are added to the water to form tiny sticky particles to

• attract the dirt particles. The combined weight of the particles becomes heavy enough to sink to the bottom.– 2nd - Filtration- the water passes through filters, some made of layers of

sand, gravel and charcoal that remove even smaller particles.– Dis-infection – a small amount of chlorine is added to kill any bacteria or

microorganisms– Storage – Water is placed in a closed tank. The water then flows from

pipes into homes.

• EPA: Environmental Protection Agency (government agency) that sets standards for safe, clean drinking water

EPA was established in 1970, a time when rivers actually caught fire!

Rail car accident set the oily Cuyahoga River on fire in 1969 Photo Credit: Cleveland State University Special Collections

Dead Fish in Grand Lake, CO1972 epa.gov

• EPA standards are guidelines for the protection of our natural water sources and the quality of water that reaches our homes

• Government agencies in states and local communities enforce laws based on the EPA standards.

• Local water providers regularly test water to make sure that it meets EPA standards.

• If any concentration (amount of a substance that is in another substance) is higher than EPA standards, the water must be treated.

• This is why the U.S. has one of the safest, cleanest water supplies.

Substance Common Source Maximum Allowed, in parts per million

Copper Natural deposits; household pipes

1.3

Cyanide Various factories 0.2

Lead Natural deposits; household pipes

0.015

Mercury Refineries, factories, landfills 0.002

Nitrite Water running off fertilized fields; sewage leaks

1

p. 51C in textbook

Treatment Process of Drinking Water

Treatment of Drinking Water

1. Water in a river or lake is piped to the treatment plant.

2. Water flows through mixers where clumping agents are added to make the dirt and bacteria clump together

• 3. water flows through a clarifying pool, the clumps sink to the bottom and water becomes clearer

• 4. water flows through coal, sand, gravel and is filtered

• 5. Chlorine is added to kill the last of the bacteria

6. Treated water leaves the plant and can be stored in water tanks so that there is plenty of water available when people need it.

• Coagulation

• Sedimentation

• 1st filtration

• 2nd filtration

• Disinfection

• Storage