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How do we make water safe to drink?

Water safety and treatment is a multi-step process. Drinking water treatment is also referred to as water purification, or the ability to produce water which limits the inclusion of specific materials thereby making it safe for human consumption. The treatment process will depend on where the source water is coming from (well, river, reservoir). From the source to your glass the process looks like this:

• Removes large debris, sticks, leaves, trash, etc.

• Process that clarifies the water, removing turbidity (cloudiness) and colour
• The process is accomplished by having a substance (precipitate) in the water which allows the organic material to bind to it
• The “floc” can be easily removed using physical methods (skimming or scrapping)

• Slow flow allows “floc” and other larger particles to float or sink respectively allowing them to be removed from the water

• Removes remaining suspended particles and any unsettled “floc”
• The most common type is sand filtration
• Other filtration types include lava filtration which uses lava pebbles and ultra-filtration which uses a polymer film with chemically formed microscopic pores

• Reduces microorganisms through chlorination, ultraviolet radiation and ozone
• Chlorination and ozone both oxidize pathogens and biologic materials still found in the water at this point in the treatment
• UV radiation causes damage to the genetic material in bacteria and protozoa, inactivating them and making them harmless
• Reduces microorganisms through chlorination, ultraviolet radiation and ozone

• Fluoridation: adds fluoride to the water by the addition of hexafluorosilicic acid which decomposes and yield fluoride ions
  • Fluoridation helps to prevent tooth decay
• Water conditioning: This is a method of reducing the effects of hard water. “Hard water” refers to water that contains large amounts of dissolved minerals. It is not harmful, although it may cause scaling and lime deposits. Water softeners replace mineral ions from calcium, magnesium and even iron with potassium and sodium ions.

Why is safe, drinkable water important?

Humans need drinking water to stay alive. Humans can live up to one month without food but can only survive about seven days without water. This means access to drinking water really is a vital component to keeping us healthy.

In North America, we have access to usable source water and top-grade water treatment facilities ensuring our drinking water is available and safe. This isn’t the case throughout the world though. In 2000, the World Health Organization, UNICEF and WSSCC reported more than 2.2. million people in mainly developing countries, die each year from water-related diseases. In fact, at any one time, half of the world’s hospital beds are occupied by patients suffering from waterborne illnesses and weekly, an estimated 42,000 people die from diseases related to low quality drinking water and lack of sanitation (WHO/UNICEF, 2005).

Scientists, technologists and researchers continue to advance our understanding of water treatment so that illness from water borne pathogens is avoidable in the future.

Where does our drinking water come from?

Even though 70% of the world’s surface is covered by water, only one per cent is considered potential drinking water. 97.5 percent is salt water and the remaining 2.5 per cent is frozen as ice caps or glaciers.

In Alberta, our drinking water comes from two main sources:

• Surface Water: Lakes, reservoirs and rivers; and
• Groundwater: Wells or springs fed by underground water sources called aquifers.

Why do we have to ‘treat’ water before we drink it?

Treating water means removing disease-causing components. ‘Treating’ means disinfecting. We disinfect water prior to drinking so humans don’t consume naturally-occurring or man-made disease-causing organisms that could make us ill.

Science Alberta Foundation wishes to thank Alberta Ingenuity Fund and the University of Lethbridge for their support