1. temperature
the degree or intensity of heat present in a substance or object
Cooler water is more suitable for drinking
Cold water = more oxygen
Hot water = more carbon dioxide

2. dissolved oxygen the level of oxygen present in water
High DO = better water
Low DO = bad water
DO comes from the air and aquatic plants

3. pH a number expressing the acidity or alkalinity of a solution
Acids have low pH (1-5)
Bases have high pH (9-14)
Good water (neutral) should be around 6-7
Organisms cannot survive in extreme pH's

4. turbidity the cloudiness or haziness of water
More turbidity = bad water
Less turbidity = ideal water
High turbid water blocks sunlight from reaching the aquatic plants so they cannot produce their food through photosynthesis

5. bioindicators
an organism whose status in an ecosystem is analyzed as an indication of the ecosystem's heath.
If these species die then the water is bad
Ex: frogs, lichens, algae, fish

6. potability Suitable for drinking
Potable water must be low temperature (cold), low turbidity(clear), and lots of DO(dissolved oxygen)

7. Nitrates and phosphates
Chemicals that can contaminate water in large amounts
Ingredients in fertilizers that gets into the water supply and causes water to go bad
Causes an abundance of algae growth in bodies of water

8. sewage waste water and excrement conveyed in sewers
Uncontrolled sewage can contaminate water supplies and cause various disease outbreaks

9. eutrophication
excessive richness of nutrients in a lake or other body of water, frequently due to runoff from the land, which causes a dense growth of plant life and death of animal life from lack of oxygen.

10. Water hardness
a measure of the amount of calcium and magnesium salts in water
Comes from weathered/eroded rock particles
Signs of hard water are spots on dishes in the dishwasher and light brownish stains on white clothes
Can be treated with water softeners