Water is one of the most vital natural resources that sustains life. Water is a colourless, odourless, tasteless, transparent chemical compound. One molecule of water contains two atoms of hydrogen and one atom oxygen. Water is a universal solvent and nontoxic liquid.

Water covers larger part of the Earth’s surface and its availability has great impact in the development of a community.

Uses of water

Water is very useful in our built environment. The uses of water include the following:

Domestic use: Drinking, cooking, bathing, washing, watering of garden, recreation etc.

Agricultural use: Irrigation

Industrial use: Manufacturing

Commercial use: Transportation, office buildings, malls, etc

Power: To generate electricity

Firefighting: water is used along with other agents to extinguish fire

Used water is disposed as waste water and can also be recycled for reuse.

Water cycle

Water cycle is the movement of water from one form to another. Water is liquid in its natural form. Water evaporates from the oceans, condenses in the sky and form clouds which later falls on the earth surface as rain.

Water keeps changing its states and undergoes three stages

Condensation stage: water is ice in its solid state.

Evaporation stage: water is vapour in its gaseous state.

Sublimation stage: water is liquid in its natural state.

Sources of water:

Water is gotten from sources such as rainwater, groundwater and surface water and stored in reservoirs. Groundwater is a good source of water for a small community while surface water is the ideal source of water for large communities and cities.

Rainwater

Rainwater is a clean source of water when collected directly from the sky, it is pure enough that it can immediately be used for domestic activities. However, caution must be taken when harvesting rainwater.

Rainwater can be contaminated with air pollutants to become acidic or acid rain most especially when you are near to chemical plants.

Rainwater can be contaminated with lead when collected through the roof because zinc roofs are quoted with lead to prevent corrosion. Lead is toxic. Rainwater can be made safe for drinking by boiling and by filtering.

Groundwater

The ground absorb rainwater and water from the ocean which becomes saturated at a point known as the water table, the water formed below this water table at aquifer is known as groundwater. The ocean and the water table are at the same level. At water table, water can discharge to form lake, spring, river etc.

The groundwater is found at the aquifer below the water table. The rate of flow of groundwater depends how permeable the ground formations are. Permeable formations are aquifers. Aquifers have fine holes or networks of fine cracks that allow water to flow through them. Groundwater is extracted in the form of well and borehole.

Surface water

Surface water is the water on the Earth’s surface, examples are: ocean, river, lake, etc.

Freshwater and Saline Water

A water is said to be saline if it contains high concentration of salt dissolved in it while freshwater contains a small amount of salt.

Freshwater: contains less than 1,000ppm of salt

Saline or salty water: ocean water contains about 35,000 ppm of salt

Water purification processes

Water in its raw form has limited uses, it is not suitable for drinking, irrigation, or many industrial uses because it has impurities in it.

The purification process of water involves collection, treatment and distribution.

Water supply

Treated water is distributed to the community for use by using plumbing system (pumps and piping systems)

Greywater

Greywater is used water from washing machine, dishwasher, shower and sink and that has not come in contact with faeces.

Stormwater

Stormwater is water from the precipitation of rain and melted ice. Stormwater soaks into the soil or remains on top of impervious surfaces like roads, sidewalks, etc., where it later runoff to another location or evaporates.