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permeable liner, and a body or superstructure for supporting and reinforcing the sidewall. The frame assembly generally features a lower rail and a top rail to that your pool sidewall is attached. The liner is attached with an internal surface of the pool sidewall along an upper edge.

History
Swimming as an organized activity extends back as far as 2500 b.c. in ancient Egypt. Actual swimming pools were invented in the first century b.c. by the Romans. In Rome and Greece, swimming was the main education of young boys. Many of the Roman pools were also heated using water diverted through piping from natural springs. The elaborate bathhouses built with marble and expensive gilding were very favored by the elite society but the majority of people continued to swim in lakes and rivers. These bathing pools were the precursors to current day swimming pools.

In Europe, many individuals refrained from building swimming pools because of the fear that infections could be caught from infected swimmers. Europeans formed their first swimming organization in 1837 in London, which at that time had six indoor pools. The popularity of swimming pool did not begin to improve until after the first modern Olympic games in 1896.

Raw Materials
Raw materials for manufacturing swimming pools consist of polyvinyl chloride (PVC) plastic, galvanized steel or metal, fiberglass, concrete, and polyurethane foam. Adequate steel bars for reinforcing a concrete pool range in dimensions from 0.38 in (0.97 cm) to 0.75 in (1.9 cm) diameter (these values vary with respect to the structural requirements of the design). All piping useful for pool plumbing is a minimum of schedule 40 PVC or the equivalent and should be stamped with American Society for Testing and Materials (ASTM) approval. The liners are usually plastics or similar materials.

Design
The range of designs for swimming pools are a reflection of the unique spatial and economic concerns of the consumer. Concrete pools are probably the most flexible with the capability to create any shape or configuration. Vinyl-lined pools are evolving into free form designs that may incorporate a larger number of design options with fiberglass pools having probably the most restrictive design elements (one-piece construction designed at the factory). Design drawings are completed showing the actual layout of the pool, including shape, elevation, and size. An engineer provides soil and structural analysis assisting in the location and optimal design for a swimming pool installation.

Soil analysis is conducted on all surfaces just before installation to make certain a structurally sound pool. A swimming also needs to have something that circulates the water from the bottom of the pool to the surface to help in the quality of the water. All pools must use grounded wiring and have breakers that protect from shorts in less than water lighting systems.

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