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90 Years of PRELOAD's History - How it Began.

The Idea

Preload’s history opens in the early 1930s with a small group of pioneering engineers exploring the possibility of using new high strength steel wire to replace steel turn-buckle designs of early 1920’s prestressed concrete tanks. Preload applied the emerging concept of embedding prestressed, high-strength steel wire inside the walls of concrete tanks. Preload recognized the concrete and reinforced steel design efficiencies and that concrete in permanent compression are significantly less prone to cracking, less permeable, and more durable and dependable. Preload developed design and construction techniques over the decade, with Preload tanks’ proliferation beginning in the 1940s.

One historical consulting engineer from the first Preload group, William S. Hewitt, was the inventor of the Hewitt System of Reinforced Concrete Construction for bridges in the 1910s. Hewitt was a significant bridge contractor in the Minneapolis area from the 1890s to the 20th century. His pioneering discoveries of reinforced and prestressed bridges ultimately led to his shift from constructing bridges to prestressed tanks.

Moreover, the following article by the Minnesota Historical Society states, “Consulting engineer William S. Hewitt invented the widely used prestressed, reinforced-concrete construction system, which utilizes an inner concrete shell strengthened by adjustable steel bands. The Minneapolis’s Washburn Park tower, erected in 1931-32, resembles a medieval fortress sheltered within its forest-like setting in southwest Minneapolis. With a holding capacity of 1.35 million gallons, it is the city’s only surviving water tower still used to store water.”

The Result

Additionally, Hewitt’s invention of prestressed concrete tanks led to the creation of thousands of long-lasting and efficient Preload prestressed concrete tanks across America. Preload pioneers discoveries and continues to break records in the prestressed concrete tank industry as time passes every year. Hewitt’s invention of prestressed tanks enabled history to be written by those who continued to come after him.

Likewise, Preload’s design and construction processes have experienced multiple advancements. Advancements include developing sliding floor/wall connection, wire-winding techniques, materials, steel shell diaphragm, and dome integration. However, the early concrete concept in compression has remained the consistent, underlying principle to Preload tanks.

Finally, after 90 years in business and approaching 4,000 tanks constructed, Preload remains the unrivaled leader in designing and building prestressed concrete tanks. Our original vision to design and develop the most durable, low-maintenance water storage structures persists today. Specifying a Preload tank ensures design and construction by the industry’s most experienced and knowledgeable team.


PRELOAD is the global pioneer of wire-wound prestressed concrete storage tanks, with more than 3,700 tanks completed to date. Ever since we constructed our first wire-wound prestressed concrete tank in the 1930s, the industry has and continues to recognize Preload as the innovator of our industry. PRELOAD serves clients across the United States with offices in Kentucky, New York, Texas, and Massachusetts.

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