Following are reasons why precast concrete tanks are considered superior to steel (and cast-in-place concrete): Precast Post Tensioned Concrete Tanks are expected to be virtually maintenance free for 50 plus years. Metal accessories such as the ladders, hatches, fasteners, etc. are manufactured of stainless steel or aluminum, to eliminate the need of any painting during the life of the tank. The roof for the tanks are typically constructed of precast concrete or aluminum. Precast Concrete Tanks do not need to be limited to above ground installations (as is required for steel water tanks for maintenance purposes). They can be either above grade, partially in ground, or backfilled to or above the roof line. The weight and structural integrity of the wall panels also allows for differential backfill in the event the tank needs to be installed in a hillside. Steel tanks normally need to be repainted on a nominal 12-year cycle. The average cost for sandblasting, removal of debris, electrical consumption for light (and heat) and re-coating a tank is approximately $2.75 per square foot for an epoxy coat (e.g. a DuPont or MAB primer plus epoxy finish). Above ground tanks need to be coated on the inside and outside surfaces. Another item to consider is the down time during the maintenance stage. The nominal "down time" for a tank while undergoing service is 37 days. During this time an alternate water source or storage capacity will need to be made available. (See the Steel Tank Maintenance Cost Analysis below.) Concrete Tanks are ballistic resistant. This can be an important factor in the selection of a tank, especially in a wooded area. A hunter's stray bullet can easily puncture the shell of most steel tanks, or fracture glass-fused-to-steel. This would normally require the tank to be dewatered and repaired at the Owner's expense. Concrete tanks remain more aesthetically pleasing during the life of the structure. Concrete tanks do not rust or change colors unevenly. The gray color of concrete is unobtrusive and generally not as noticeable as a steel tank, especially after the first 10 years. Compared to cast-in-place concrete tanks or AWWA D110 wire wound prestressed concrete tanks, Precast Post Tensioned tanks are very cost competitive. The on site erection time is also much shorter than with other types of concrete tanks, which can reduce the cost of the Engineer, job site inspector, and supervisor. Precast Post Tensioned Tanks can also be erected during colder temperatures if necessary since the walls and roof are cast in a shop with a controlled environment. Precast tank panels are manufactured in a horizontal position, which allows for precise reinforcement and penetration placement. Cast-in-place tanks are constructed in a vertical position, which leaves more room for error in construction. Precast post-tensioned tanks manufactured by Dutchland, Inc. are steel form finished on the exterior side and hand finished on the interior side. Wood forms are not used. There is no better looking or more functional tank then one manufactured and constructed by Dutchland, Inc.   Steel Tank Maintenance Cost Analysis: Following are estimates for sandblasting, primer, and finish coat maintenance sessions for five different tank sizes. The total costs per size are based on four maintenance sessions for the life of the tank. Tank coating square footage and sandblasting/coating cost estimates per session: 50,000 gallon tank: (17' high x 23' diameter is 1,650 sq. ft x 2 sides = 3,300 sq. ft. at $2.75/sq. ft.) $9,075 per session 100,000 gallon tank: (21' high x 30' diameter is 2,700 sq. ft x 2 sides = 5,400 sq. ft. at $2.75/sq. ft.) $14,850 per session 500,000 gallon tank: (22' high x 64' diameter is 7,700 sq. ft x 2 sides = 15,400 sq. ft at $2.75/sq. ft.) $42,350 per session 1 million gallon tank: (30' high x 78' diameter is 12,200 sq. ft x 2 sides = 24,400 sq. ft at $2.75/sq. ft.) $67,100 per session 2 million gallon tank: (40' high x 94' diameter is 18,800 sq. ft x 2 sides = 37,600 sq. ft at $2.75/sq. ft.) $103,400 per session If the owner of a steel tank is not equipped with a spare tank or another structure, which can be used for temporary storage, an alternate temporary solution will need to be provided to supply water. This is done with a temporary store and pump service. Costs are estimated based on quotes as defined below, which can vary greatly depending on the individual need. Temporary store and pump system cost estimates per session (based on the tank being out of service for 37 days): 50,000 gallon steel tank = $10,600 100,000 gallon steel tank = $11,900 500,000 gallon steel tank = $13,600 1 million gallon steel tank = $15,000 2 million gallon steel tank = $16,600 There are many other incidental costs associated with steel tank coating such as the need for respirators, ventilation, access, lighting, power, etc. which are not considered in these estimates.   TOTAL MAINTENANCE ESTIMATE FOR A STEEL TANK (Sandblasting/coating plus temporary store and pump system) 50,000 gallon tank = $19,675 per session, or $78,700 for four sessions 100,000 gallon tank = $26,750 per session, or $107,000 for four sessions 500,000 gallon tank = $55,950 per session, or $223,800 for four sessions 1 million gallon tank = $82,100 per session, or $328,400 for four sessions 2 million gallon tank = $120,000 per session, or $480,000 for four sessions Many times, the cost difference of a steel tank versus a precast concrete tank is less than the first maintenance session. Occasionally, precast concrete tank bids are less than steel tank bids. Precast concrete tanks and other precast concrete products are considered to be the superior product of choice for many applications. Click here to view an open letter by Jorgensen, Hendrickson and Close Engineers, Inc. (an expert in the industry) to other engineers who specify AWWA D110 and AWWA D115 tanks.