6.2 WATER SUPPLY Classification of Water Without water, life would be impossible: it is fundamental to the survival of man and all living things. There are two different types of water that are able to meet our water supply needs: : it includes any freshwater which comes from , stream systems, and lakes; Surface water wetlands : it exists in subterranean that are situated underground. Groundwater aquifers 1 DO What is the purpose of a ? 1 well Uses of Water Potable or drinking water comes from both sources. Ground and surface water are normally used in for drinking, cooking and other activities, but surface water is also used in other ways, for example in agriculture and to generate electricity. 1 households MORE In Italy, we still get water from the same sources as the Romans 2,000 years ago. The primary source is rivers and springs (surface water) followed by groundwater. For example, Rome receives 97% of its drinking water from springs and 3% from wells. 1 Differences While surface water is freshwater that exists above ground and is exposed to evaporation, the groundwater contained in the Earth is situated under the surface: surface water recharges underground water through the rainwater that drips deep into the ground or from melting snow and glaciers. While groundwater is typically cleaner than surface water, it can still contain various contaminants: pesticides, animal waste, insecticides, algae, industrial waste and other organic materials present in the surface water reach the underground water through soil percolation. Unlike surface water, ground water is free from pathogenic organisms such as salmonella and malaria. Their chemical composition is quite different: for example, surface water shows less salt content; as depth increases, salt and minerals contents increase in groundwater. Wastewater is classified into two categories: Wastewater : it comes from sinks, washing machines, and bathtubs. For this reason, it includes soapy water, too. It contains a lower level of contaminants than blackwater and is easier to treat and process; Greywater : it is wastewater from bathrooms and toilets that contains faecal matter and urine. Also called or brown water, it can carry disease caused by bacteria that are harmful to man. Blackwater sewage They must be kept in separate tanks because, although they are both used water, they have different levels of contamination and must be treated differently. They can be recycled through filtration, distillation and several other mechanical or biological treatment systems.