Water is less dense as ice than as liquid. This is why ice floats.
On a hot day, water drops form on a cool glass of water because the coolness causes the evaporated water in the air to turn back to a liquid. This is called condensation.

NORTH TABLE MOUNTAIN WATER AND SANITATION DISTRICT

WATER EDUCATION
Water Purification

There are several different ways to treat drinking water. Water treatment facilities may use any one of them or a combination of them. The treatment process chosen will be determined by the origin of the water as well as the quality of the water. Some water sources do not need any treatment at all, while others may need several treatment processes. Chlorine gererator used to make disinfecting chlorine.Some of the different processes are as follows:
  • Flocculation / Sedimentation - This process is probably the most common. Simply put, small, unwanted particles in the water are combined to create larger, heavier particles. As these particles become denser than the water, they sink to the bottom of the water tank. The clarified water is left on top which is then siphoned off for more treatment.
  • Filtration - This process is used to remove microorganisms, clay, silt, and unwanted organic materials. Filtration is also effective in removing some metals such as iron and manganese. An example of this process, on a small scale, would be the water filtration systems that some people put on their taps at home.
  • Ion Exchange - The basic idea for this process is to cause a chemical reaction that will force unwanted ions in the water be replaced with desired ions. Synthesized resins (natural resins can also be used) are covered with replacement ions such as OH-, Na+, H+ or Cl- and then added to the Filtration Beds used for filtering water.untreated water. The unwanted ions in the untreated water then attach themselves to the resins and the replacement ions from the resins take the place of the removed ions, thus creating a purer water. The resins are used up once all of the replacement ions are stripped from the resins. The resins can be recharged by washing the resins with a solution containing a strong concentration of replacement ions. The ion exchange process is great for softening hard water. It is also very successful in removing several metals such as arsenic, chromium, excess fluoride, nitrates, radium, and uranium.
  • Absorption - This is done by filtering water through activated carbon granules. The carbon granules "absorb" the unwanted contaminants until the granules are saturated. The granules then need to be either replaced or heated to a very high temperature which will burn off the contaminants.
  • Disinfection - By using chemicals such as chlorine, dangerous microorganisms are killed in the water. These microorganisms can be as dangerous as to cause health related problems or as harmless as to only cause bad odor in the water. Other disinfectants that can be used are ozone, and ultraviolet radiation.