Multi-Column Elevated Storage Tank (LEG)

Double Ellipsoidal (DE) for 150,000 gallons and smaller or Torus Bottom (TB) for 200,000 gallons and larger

DEFINITION: An elevated welded carbon-steel water storage tank supported by a series of carbon-steel supporting columns and cross braces.

Positive Uses (when it's best)

  • Most economical style in small and medium capacities
  • To gain additional storage capacity in the water system (especially for fire protection)
  • To gain additional pressure in the water system (especially for power outages)

Highlights & Advantages (over other styles)

  • Traditional elevated storage tank design (Caldwell has been building this style since 1887. In the beginning, they were wooden, then riveted steel, then welded steel with the last wooden tank sold and supported in 1986)
  • Caldwell's Multi-Column Tank is the most economical means of providing elevated water storage capacity in sizes 1,000,000 gallons and smaller but many factors play into this
  • Most efficient use of steel in the elevated tanks category
  • Normally the center column is a 'wet riser', meaning that it is flooded with water from the ground up into the tank
  • Standard designs include a balcony and handrail around the tank with access ladders on the tower column and tank, all of which provide useful exterior access

Special Features (bonus part of asset)

  • Some believe this style provides the easiest additional future antennae because of its external balcony.
  • In locations where there is an increased risk of seismic events or high winds, additional design requirements can be most cost effectively met utilizing the Multi-Column tank style.
  • Caldwell Tanks has constructed many special capacity tanks and numerous unique design Multi-Column tanks for product display such as Walt Disney's "Mickey Mouse Tank" in Lake Buena Vista, Florida, Brook's Catsup Bottle in Collinsville, Illinois, and Brown-Forman's Bourbon Bottle in Louisville, Kentucky.

Standard Sizes (others available but may be at a premium)

  • Reference the table 50,000 to 2,000,000 gallons

Standard Accessories
American Water Works Association (AWWA D100 & D102)

  • Steel frost-proof pressure/vacuum relief vent designed for maximum protection
  • (1) 24" diameter roof hatch with hinged cover and hasp
  • (1) 24" diameter roof hatch bolted for attachment of exhaust fan
  • (1) 18" x 24" riser manhole
  • Purchaser-specified inlet/outlet connection to riser
  • Balcony with OSHA compliant handrail
  • Grounding for minimizing lightning damage
  • Exterior tank and tower ladders with OSHA compliant safety climb devices
  • Tower supported overflow pipe to grade level with concrete splash pad

Elective Accessories
Collective in the Water Tank Industry

  • Tank drain for washouts
  • Larger diameter manholes and hatches
  • Shell manhole with ladder inside center wet riser
  • Interior tank ladders (not recommended in colder climates)
  • Complete internal seal welding
  • Roof handrails
  • Aluminum or custom roof vent
  • Cellular antenna supports and provisions
  • Painted logo, lettering, and custom graphics
  • FAA lighting
  • Locking ladder gates
  • Ladder cages
  • Dry riser with ladders and lighting in access tube and insulated tank piping
  • Overflow flap valve
  • High water elevation/pressure gauge
  • One pressure testing port on each column leg for seal weld verification
  • Solar powered or other type of mixing system
  • Additional security or ornamental lighting
  • Specialty trim or customized design

Specifications & Standard Tank Drawing

Caldwell Drawings & Specs

Standard Sizes : LEG

(US Gallons)
Head Range
Tank Diameter
50,000 17'3" 24' 4
75,000 19'3" 28' 4
100,000 22' 30' 4
125,000 24'1" 32' 4
150,000 28'3" 32' 4
200,000 28'3" 36' 4
250,000 25'6" 43' 5
300,000 30' 43' 5
400,000 30' 50' 6
500,000 37' 50' 6
500,000 30' 56' 6
600,000 36' 56' 6
750,000 38'9" 60' 8
750,000 33'10" 65' 8'
1,000,000 38'9" 70' 8
1,000,000 33' 77' 9
1,500,000 35' 91' 12
2,000,000 34'9" 105' 14

Surveys from Actual Caldwell Tank projects

Case Studies for Actual Caldwell Tank projects

Caldwell Connect