Pedesphere Elevated Storage Tank (PED)

DEFINITION: An elevated welded carbon-steel spherical water storage tank supported by a single cylindrical carbon-steel support pedestal with a flared conical base.

Positive Uses (when it's best)

  • Largest selection of standard tank sizes
  • 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)

  • Caldwell's Pedesphere Tank is sphere-shaped in capacities from 25,000 gallons to 150,000 gallons and is spheroidal-shaped for larger capacities
  • Attractive, sleek, simplistic appearance
  • Beneficial in specific types of soil and seismic conditions
  • The smooth, continuous exterior surface and reduced overall surface area offer future maintenance benefits.
  • Interior ladders and piping protects against weather and vandalism and easily allows for pipe insulation
  • The pedestal shaft and flared base cone diameters are varied to suit individual design requirements and owner conditions

Special Features (bonus part of asset)

  • The slender single support column, which does not contain water, securely encloses the access ladders and connecting piping to the tank.
  • In larger sized PED's, the base provides lockable storage for pumps, piping, controls, or extra storage.
  • Some believe this to be the most aesthetically pleasing tank style because of its simple, contoured shape, its small ‘sky-print' (the equivalent of a footprint in the sky) , and its small ground silhouette (shadow on the ground).
  • SPECIALTY: Additionally, Caldwell Tanks has constructed countless other special designs to meet the requirements of our customers, like the “Exploded Cube” sculpture for Bellarmine University, the “Ad Astra” Sculpture for the University of Louisville, and most recently Hillerich & Bradsby's “Louisville Slugger Bat” in Louisville, Kentucky serving as the building's HVAC vent.

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

  • Reference the table 50,000 to 1,500,000

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) 24" diameter access tube roof hatch
  • (1) 18" x 24" diameter manhole in base of access tube
  • (1) 24" diameter painter hatch at top of pedestal
  • Purchaser-specified inlet/outlet piping with expansion joint
  • Pedestal-supported overflow pipe to grade level with concrete splash pad
  • Base cone, pedestal, and access tube ladders with OSHA compliant safety climb devices
  • Platform landing at top of pedestal
  • Painter's rings near top of pedestal
  • Interior lighting in pedestal and in access tube
  • Grounding for minimizing lightning damage
  • Condensate ceiling (steel with a drain to the overflow pipe)
  • Personnel door in base cone (36" x 80")
  • Gravel floor inside base

Elective Accessories
Collective in the Water Tank Industry

  • Tank drain for washouts
  • Larger diameter manholes, hatches, and access tube
  • Intermediate rest platforms
  • Complete internal seal welding
  • Roof handrail or exterior ladder up the pedestal
  • Aluminum or custom roof vent
  • Cellular antenna supports and provisions
  • Painted logo, lettering, and custom graphics
  • FAA lighting
  • Insulated and/or heat traced tank piping or stainless steel piping
  • Piping in base cone - bypass lines, altitude valve, etc.
  • Overflow flap valve
  • High water elevation/pressure gauge
  • Concrete floor inside base
  • Instrumentation, control room, & cathodic protection
  • 8' or 10' wide overhead door
  • 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 : PED

(US Gallons)
Shape Head Range
Tank Diameter
50,000 sphere 21'3" 24'
75,000 sphere 25'6" 27'
100,000 sphere 25'6" 30'
125,000 sphere 29'6" 32'
150,000 sphere 32'3" 34'
200,000 spheroid 28'3" 41'
250,000 spheroid 31' 43'8"
300,000 spheroid 33' 46'6"
400,000 spheroid 35'6" 51'6"
500,000 spheroid 37'6" 55'6"
600,000 spheroid 38'6" 60'
750,000 spheroid 40' 66'
1,000,000 spheroid 40' 74'
1,250,000 spheroid 40' 80'
1,500,000 spheroid 48' 84'

Surveys from Actual Caldwell Tank projects

Case Studies for Actual Caldwell Tank projects

Caldwell Connect