Fresh water

Aquifer

Underground layer of rock, sand, or gravel that stores groundwater; acts like an underground reservoir

Grey Water

Water already used in sinks, showers, and washing machines; safe to reuse for toilets, irrigation, and cleaning, but NOT for drinking.

BOD (Biochemical Oxygen Demand)

Amount of oxygen microorganisms need to break down organic waste in water; high BOD = low oxygen = polluted water

Eutrophic / Eutrophication

A nutrient-rich, algae-filled water body caused by excess nitrogen and phosphorus (fertilizers/sewage); leads to low oxygen and fish kills

Point Source Pollution

Pollution that comes from a single, identifiable source like a pipe, sewer, or factory discharge

Groundwater

Freshwater stored underground in aquifers

Nonpoint Source Pollution

Pollution that doesn’t come from one place—spread-out sources like farms, streets, and stormwater runoff

Oligotrophic

Clear, low-nutrient water with high oxygen levels and healthy aquatic life

Sewage

Wastewater from toilets, sinks, and drains; contains organic waste that increases BOD

Nutrient Pollution

Excess nitrogen and phosphorus that cause algal blooms and eutrophication