opinion
What is water?
“It may come as a surprise to some that you can’t suck water. You can push water, but you cannot pull it.”
By Cal Stanley
T
his is the first of a series of articles about water. That stuff that comes out of the tap and also seems to be in every swimming pool. The good ones anyway. Both humanity and the swimming pool industry are totally reliant on water. Without it neither humans, animals nor swimming pools would exist. So I thought it may be worthwhile to investigate this substance that we can’t do without. Water is a precise mixture of hydrogen and oxygen known as H2O. One molecule of water has two hydrogen atoms bonded to one atom of oxygen. Each water molecule’s hydrogen atoms, being positively charged, bond with the negatively charged oxygen atom of another molecule and vice versa. Thus, there are a number of connectivity bonds between these molecules. This is also what causes surface tension and capillary action. Most substances on our planet exist in solid, liquid or vapour form. Water is one of those very rare substances that exists in all three forms, as ice, water and water vapour.
Where is all of our water?
• Water covers 70 per cent of the Earth’s surface; • 97 per cent of water is found in the oceans and seas of our planet; • 2 per cent is stored in the polar ice caps; • 0.6 per cent is found in the earth’s rivers and lakes; and • 0.4 per cent is underground. That’s the water you can see, find, and feel. Not forgetting that water also forms about 75 per cent to 80 per cent of every human and animal body on the earth. 28
SPLASH!
April/May 2022
Throw in a handful of earth and about 12 kg of carbon and look what you get. A human body! Doesn’t sound like much does it, but consider what we all get from it. That’s right, no water would mean no life. Worse still, no life would mean no swimming pools!
Relative density
All substances on Earth have a relative density (RD) and they are all in relation to a base mark of 1.0, which happens to be the relative density of fresh clean water at 40C. Another term for relative density is specific gravity. The actual density of fresh water varies with its temperature, but the variation is small and not relevant for most purposes. Any article or substance with a density less than 1.0 will float on water, and anything with a density more than 1.0 will sink in water. Some common densities: Water Sea Water Air (at sea level) Hydrochloric Acid Crude oil Petrol Mercury Beer PVC pipes Balsa wood Ebony Eucalyptus (wandoo)
1.000 1.025 0.00145 1.200 0.918 0.739 13.633 1.040 1.400 0.170 1.120 1.140