What is Safe Drinking Water? (Elementary)



There are two major sources of water:

  • Groundwater - found below the ground where it accumulated in between soil and rocks. The volume of water can range from small to very large similar to above ground creeks, rivers and lakes.
  • Surface water - found on the Earth's surface in lakes, ponds, rivers, etc.

Drinking water should be:

  • Clear
  • Colourless
  • Odourless

Drinking water should not contain:

  • Small, living organisms
  • Nutrients
  • Chemicals

Where do harmful particles come from?

  • Erosion of rock and soil
  • Garbage landfills
  • Sewage
  • Wastewater treatment plants
  • Farms
  • Homes
  • Water from large companies or factories
  • Motor boats like jet-skis

Effects of harmful particles in water

  • Appearance - can taste, smell, or look bad
  • Appearance of people drinking bad water - skin rashes, bad teeth
  • Harmful effects within hours - diarrhea and/or vomiting
  • Harmful effects not seen for years - liver disease, cancer

Minerals, nutrients and chemicals can affect human health

  • As water moves, it dissolves and carries with it things it contacts.
  • Many salts and minerals found in water are necessary for our bodies, but some like arsenic can be dangerous.

Microorganisms and human health

  • Microorganisms are small, living organisms that can make you sick, including: bacteria (ex: E. coli), Protozoa (ex: cryptosporidium), viruses (ex: Hepatitis A), algae (ex: microcystis).
  • However, not all microorganisms found in water can make you sick.

Some minerals and nutrients affect human health

  • High levels of sulfates and other salts can cause diarrhea.
  • Nitrates can cause death in babies.
  • High levels of arsenic can cause heart disease and cancer.

Chemicals can affect human health

  • Many of the harmful chemicals are man-made.
  • Some include farm chemicals (pesticides), oil and gas.
  • Effects may include liver or kidney damage, cancer.

How do we make our water safe?

  • Monitor the water supply.
  • Test for harmful particles.
  • Apply appropriate treatment before drinking the water.
  • Protect the source water.


  • All water should be treated before drinking.
  • No one treatment system is perfect for every water source.
  • Problems with the water must be identified, then treated.
  • Just adding chlorine to your water does not make it safe.

Differences between farm water and city water

  • Cities can have water tested daily in water treatment plants.
  • Some farms may have wells tested twice a year.
  • Farms get water from wells or ponds, while in the city, water comes mostly from lakes and rivers.
  • Water in cities contains high levels of chlorine while some farms don't use chlorine.
  • Farm water is often of much poorer quality than city water.