Despite making up a third of the world's surface, water, the universal solvent, is a rare source and must be treated to be made available for human consumption. Water is structured on a molecular level to be able to dissolve a variety of different substances, so it is considered a good solvent. It is a folded molecule as it has a polar arrangement of oxygen (negatively charged) and hydrogen (positively charged) atoms. Water is easily attracted to other molecules, sometimes to the point of breaking the attractive forces and dissolving it (Perlman, 2014). Water quality is based on both chemical and aesthetic factors. To determine the quality of the water, the temperature, pH, TDS (total dissolved solids), dissolved oxygen and turbidity of the water will be tested. Temperature affects chemical elements, primarily dissolved oxygen levels in surface waters, and biological properties such as photosynthesis of aquatic plants and more. Warm water has less capacity to hold dissolved oxygen and the solubility of oxygen decreases. As the temperature increases, an exothermic reaction occurs resulting in the release of heat in the form of gas molecules. Kinetic energy increases the motion of gas molecules, breaking intermolecular bonds and separating them from water molecules. As a result, the amount of solute available to dissolve in water is less. Thermal pollution is another serious problem caused when water sources (such as streams) are warmer than the body of water they join. This can result from urban runoff such as heated water on streets, industrial wastewater, hot water used to cool equipment, and the removal of covers that reduce shade, increase erosion, and result in more sediment in the 'water (Unknown, n.d.). This can lead to an increase in TDS in the water. TDS measures the co...... center of the paper...... SDW, nd TDS and pH. [Online]Available at: www.safewater.org/PDFS/resourcesknowthefacts/TDS_AND%20_pH.pdf[Accessed 11 May 2104].Frey, RC a. R., 1998. Water hardness experiment: inorganic reactions. [Online]Available at: www.chemistry.wustl.edu/-edudev/LabTutorials/WaterFreshWater/hardness.html[Accessed May 5, 2014].Johnson, R., Holman, S. & Holmquist, D., 1999. Water Quality Test Summary. [Online]Available at: www.sasta.asn.au/v2/adc/datalogging/DataSinglePagePDFs/ADCBookDatalog13-23.pdf[Accessed 15 May 2014].Perlman, H., 2014. The USGS Water Science School. [Online]Available at: http://water.usgs.gov/edu/qa-solvent.html[Accessed May 5, 2014].Unknown, nd RAMP, Regional Aquatics Monitoring Program. [Online]Available at: www.ramp-alberta.org/river/water+sediment+quality/chemical/temperature+nd+dissolved+oxygen.aspx[Accessed May 10 2014].