Topic 2: Storage Types
Drinking water can be stored in different types of reservoirs depending on local topography, hydraulic requirements, available land, construction costs, and operational objectives. The choice of storage type has a direct influence on system reliability, water quality, maintenance requirements, and energy consumption.
Among the many storage concepts used worldwide, buried reservoirs and water towers are the most common solutions for municipal drinking water supply systems.
Buried Reservoirs
Description
Buried reservoirs are storage facilities that are fully or partially constructed below ground level. They are typically located on elevated terrain so that the stored water can be distributed through the network using gravity.
In modern water supply systems, buried reservoirs have become the preferred storage solution due to their excellent protection against environmental influences and their ability to maintain stable water quality conditions.
Because most of the structure is covered by soil, the stored water is naturally protected from solar radiation, temperature fluctuations, and external contamination risks.
How It Works
Water from wells, springs, or treatment plants is transported into the reservoir and stored until required by the distribution system.
When consumers use water, the stored volume flows from the reservoir into the network. If the reservoir is located at a sufficient elevation, gravity provides the necessary pressure for distribution.
This arrangement allows water production and water consumption to occur independently while maintaining stable hydraulic conditions.
Advantages
- stable water temperatures throughout the year
- excellent protection against sunlight and weather conditions
- reduced risk of biological growth caused by temperature fluctuations
- high level of protection against external contamination
- long service life with relatively low maintenance requirements
- visually unobtrusive and well integrated into the surrounding landscape
- highly reliable operation with minimal energy requirements when combined with gravity-fed systems
Disadvantages
- requires suitable topography with sufficient elevation
- excavation and construction can be costly depending on ground conditions
- inspections and structural modifications may be more complex than in above-ground facilities
Typical Applications
- modern municipal water supply systems
- regional water supply schemes
- gravity-fed distribution systems
- large storage facilities serving towns and cities
- systems prioritizing water quality and operational reliability
Water Towers
Description
Water towers are elevated storage structures that combine water storage and pressure generation within a single facility.
Unlike buried reservoirs, which rely on natural terrain elevation, water towers create hydraulic pressure by storing water at a significant height above the surrounding service area. The elevated water level generates pressure that can be distributed throughout the network without continuous pumping.
Historically, water towers played a central role in urban water supply systems and continue to be used where natural high ground is unavailable.
How It Works
Water is pumped into an elevated storage tank located at the top of the tower structure.
As consumers use water, gravity causes water to flow from the elevated tank into the distribution network. The height of the water column determines the available pressure within the system.
The tower therefore serves two functions simultaneously:
- drinking water storage
- hydraulic pressure generation
Advantages
- combines storage and pressure generation in one structure
- reduces dependence on continuous pumping during normal operation
- requires relatively little land area compared to large reservoirs
- provides visible emergency storage capacity
- can stabilize pressure fluctuations within the network
Disadvantages
- high construction and structural engineering costs
- complex maintenance due to elevated access requirements
- greater exposure to environmental conditions and temperature fluctuations
- visual impact on the surrounding landscape
- generally higher lifecycle costs than buried reservoirs
Typical Applications
- urban water supply systems
- flat regions without suitable natural elevation
- historic municipal infrastructure
- industrial facilities requiring elevated storage
- areas where land availability is limited but pressure generation is required
Summary
Both buried reservoirs and water towers perform the essential function of storing drinking water and supporting reliable distribution. However, they achieve this in different ways.
Buried reservoirs are the preferred solution in most modern water supply systems due to their excellent water quality protection, stable temperatures, and long service life. They are particularly effective when suitable elevated terrain is available.
Water towers, on the other hand, remain valuable in flat regions where natural elevation is lacking. By combining storage and pressure generation within a single structure, they provide a practical solution despite higher construction and maintenance costs.