The 6 steps in the urban water cycle

Thorough knowledge of all the processes involved in the urban water cycle is essential to attain sustainable, efficient water management.

This cycle enables us to carry out seemingly simple daily actions, such as filling a glass of water in our kitchen. However, these actions actually hide complex relationships and interconnections.

The urban water cycle is the general process that covers supply and sanitation services. It begins with how water is captured and ends with the appropriate discharge of water into the environment. The 6 stages in the urban water cycle are fundamental processes in our day-to-day lives.

1. Source

First, we need to obtain the volume of water required for human and industrial consumption from nature. This is known as water catchment. This can be done in different ways: a) from surface water, such as reservoirs, intakes from water courses, etc.; b) or from groundwater, such as wells connected to aquifers.

In some cases, water catchment comes from reuse processes, in which the water obtained is generally used for purposes other than human consumption, such as watering gardens and street cleaning. Recently, due to growing water scarcity in certain parts of the planet, extensive research is being carried out to ensure tertiary water is suitable for human consumption.

2. Water treatment

Raw water must be treated to make it suitable for human consumption. This is the purpose of Drinking Water Treatment Plants (DWTP), which combine different technologies such as coagulation, sedimentation, filtration and chlorination. They all pursue the same goal as the first plants opened in Scotland in the 19th century which, in light of their success, were replicated across the world.

New technologies are currently being developed to improve the drinking water treatment processes performed in these DWTPs.

Water filtration pond

3. Water storage

Once water has been made drinkable, it is transported to urban water tanks connected to the supply network. Their objective is to ensure a continuous supply of drinking water under controlled parameters. They also safeguard the future provision of water by storing surpluses when they are available.

For this purpose, tanks are placed at different strategic points. Water is supplied via pumping stations or by gravity, when they are located at altitude.

4. Water distribution

Drinking water distribution is divided into main and secondary networks. The main network is used to distribute water from treatment plants to cities through a network of large diameter pipes (800-1600 mm). It leads into each point of supply via medium diameter pipes (450-800 mm).

Once water reaches the supply points, the secondary network is used to distribute water to homes via smaller pipes.

5. Collection

After water has been used and discharged, it is collected. The sewage network consists of pipes and conduits that collect and transport the surplus water and wastewater from homes to treatment plants. Its design has to take into account many variables. These include DMA diameters to accommodate new urban developments and field orography to calculate the normal water speed in each DMA and the behaviour of the network in the event of heavy rain.

New technologies are currently offering innovative sensor and modelling techniques for this type of network to improve decision-making in the facilities in the next stage of the water cycle.

6. Water treatment

The wastewater collected by the sewage network is sent to Wastewater Treatment Plants (WWTP). It then undergoes a complex treatment process which consists of different phases and is based on physical-chemical and biological techniques (roughing, degreasing, decanting, activated sludge, biological reactor, biodiscs, microfiltration, etc.) in order to eliminate and/or reduce contaminants that are potentially dangerous to nature. Thus, thanks to these facilities we are able to reuse water and return it to the environment with the lowest possible impact.

Progress in technology optimizes this process, increasing the quality and availability of our most precious resource.

Services and solutions for the urban water cycle

Idrica’s services and technological solutions provide the necessary tools to manage the urban water cycle. This enables organizations to comply with the highest levels of efficiency, transparency and sustainability. These processes can be monitored and controlled via the GoAigua technological solution to provide a holistic overview of the entire water cycle.

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