Structural design of water tanks and pools
Structures that must not only stand but also not leak.
Photo: Julia Taubitz / Unsplash
A concrete water tank or pool is designed to stricter requirements than an ordinary structure, because besides standing it must be watertight: the NSR-10 devotes Chapter C.23 to them. DDES designs buried and elevated tanks, pools and pump rooms, and reviews their construction.
- Code
- NSR-10, Chapter C.23
- Service
- Structural design
- For
- Housing, industry, homes
What to have at hand
- Tank capacity or pool dimensions.
- Whether it is buried, on grade or elevated, and on what.
- The project's soil study.
- Architectural or plumbing drawings, if they exist.
How we solve it
- Definition of loads: water, soil, uplift and earthquake, including water sloshing in the tank.
- Design of walls and slabs with crack control so they don't leak (Chapter C.23).
- Details of joints, waterstops and pipe sleeves.
- Drawings, calculations and the watertightness test on site.
What changes compared with an ordinary structure?
Chapter C.23 of the NSR-10 limits cracking and steel stresses under service loads, and asks for more cover and better concrete, because a crack that wouldn't matter in a building lets water through in a tank and corrodes the reinforcement.
And pools in residential complexes?
At Altos de Solemio, DDES followed as interventoría (construction oversight) the construction of the complex's pools, water tank and plant rooms, with watertightness tests.
Technical notes
Concrete near the sea: what the NSR-10 requires against salt air
Exposure class C2, a water-cement ratio of 0.40, 35 MPa and concrete cover: the code's recipe for the coast.
Chlorides and reinforcement: the concrete cover that actually protects
Why the sea breeze corrodes concrete from the inside, and what to specify to prevent it.
Concrete cylinder tests: when the NSR-10 accepts the concrete
How many samples to take, how they are evaluated and what happens if a result comes out low: section C.5.6.
Frequently asked questions
Does a water tank need a structural design?
Yes. It carries large water and soil loads, and the NSR-10 sets its own cracking and durability requirements (Chapter C.23).
What is a watertightness test?
The tank or pool is filled and checked over several days for any drop in level or damp patches, before waterproofing and handover.
Does an elevated tank on top of a building change the building's design?
Yes. Water on top adds mass at the highest point, which increases seismic forces; the building must be designed with that weight.
Other situations
- Adding a second floorBefore adding a floor you need to know whether the house can carry it.
- Home structural retrofitSo an older structure resists what today's code requires.
- Crack assessmentNot every crack is serious, but every crack that grows needs to be studied.
- Warehouse designFrames, roof, floor slab and foundation, designed together.
- Retaining wallsFor basements, level changes and sloping lots.
- Steel mezzanineMore usable floor area inside the same warehouse or store.
- Building permitWhich structural documents the curaduría asks for and who signs them.
Last updated:
Contact
Building a tank or a pool?
Tell us the capacity or size and where it goes. A DDES engineer replies.
Our team works in Spanish. You can write to us in English and we will get back to you.
Photo: Ricardo Gómez Ángel / Unsplash