At 1020 Spring Street (Ten Twenty Spring) in Midtown Atlanta, the rainwater harvesting system was designed with one clear mission: provide cooling tower makeup water—exclusively.
That focus matters, because cooling towers represent one of the most consistent, high-volume non-potable water demands in a commercial high-rise. And once a building reaches roughly 7 stories or taller, cooling tower makeup demand is often strong enough that the system can use essentially all the rainwater that hits the rooftop (depending on rainfall patterns, operating hours, and tower load).
This is exactly the kind of application where rainwater harvesting shines: steady demand, predictable control strategy, and real measurable offset of potable water use.
A modern Midtown tower with real water demand
Ten Twenty Spring is part of the Spring Quarter district and is positioned as a high-performance, hospitality-forward office destination. The tower is 25 stories and roughly 525,000 SF of Class-A office, with ~32,000 SF floor plates and major tenant amenities and terraces.
In other words: it’s a large building, with large mechanical loads—exactly the environment where rooftop rainwater capture can become a meaningful utility strategy instead of a token sustainability feature.
Atlanta requires stormwater management—and rainwater harvesting can help meet it
In Atlanta, post-development stormwater management is required for new development and redevelopment. The City’s Post-Development Stormwater Management Ordinance requires projects to manage the first inch (1.0”) of rainfall using green infrastructure. That’s the minimum; we recommend about 1 gallon per s.f. of impervious.
This is where rainwater harvesting earns double credit: a properly designed capture-and-reuse system can function as a stormwater management device by reducing runoff volume through capture, filtration, and reuse. The City explicitly includes cisterns as a green infrastructure approach intended to capture stormwater for reuse.
And the City’s ordinance update Q&A materials get even more specific: rainwater harvesting and reuse systems must be designed around the demand they serve and include a plan to draw down stored water so capacity is available for the next storm—exactly why cooling tower makeup is such a strong match. Even during an Atlanta winter, a large 25 story building like this will need air conditioning in places.
The payoff: potable water savings that actually matter
Because cooling towers can consume water day after day, this approach can save hundreds of thousands of gallons of potable water over time—often more—by substituting harvested rainwater for municipal supply.
That’s good for the building owner (utility savings and resilience), and it’s good for the broader community by supporting Atlanta’s water conservation goals and reducing stress on infrastructure.
The system philosophy: do the job well, without extra complexity
This system was designed in-house and installed by McKenney’s Inc., creating a streamlined design-build workflow from engineering through commissioning. For 1020 Spring, the equipment stack is intentionally clean and operator-friendly:
- Concrete cistern for storage
- Single pump for delivery to the cooling tower makeup system
- Orival ORG sediment filtration doing most of the particulate removal
- Yaskawa iQpump VFD handling all pump controls
No unnecessary layers. No “controls sprawl.” Just a system that’s built to run.
Concrete cistern: durable, stable, and built for long service life
Concrete storage is a great fit for dense urban sites and high-use applications. It’s robust, stable, and well suited to long-term ownership—especially when the system is expected to operate routinely, not occasionally.
Orival ORG sediment filters: doing the heavy lifting
Rooftop runoff can carry a surprising amount of fine material—dust, pollen, and city grit. The Orival ORG sediment filters are designed to remove that load so downstream equipment (pump components, makeup controls, tower internals, and treatment systems) don’t become the filter of last resort. When filtration is doing most of the work, everything downstream tends to last longer and run cleaner.
Why we love the Yaskawa iQpump VFD on projects like this
We use a lot of drives across water applications, but the Yaskawa iQpump VFD stands out on rainwater systems because it can execute the controls we want without requiring a separate PLC and touchscreen.
That one decision has big long-term benefits for building operators:
- Fewer devices to fail.
- Fewer communication handoffs between “panel logic” and “drive logic”
- No programming language to learn. No proprietary code.
- Easier troubleshooting for technicians. Excellent support directly from Yaskawa.
- A cleaner, more serviceable control architecture overall.
Cooling tower makeup applications typically need reliable pressure/flow control, robust pump protection, clear alarm handling, and straightforward enable/disable and interlock logic. The iQpump platform is a great fit for that “do it right, but don’t overcomplicate it” control strategy.
Why cooling tower makeup is the perfect demand for stormwater-focused harvesting
The City’s guidance emphasizes that harvesting systems should be sized and operated with a plan to draw down storage so there’s capacity available for future storms.
That’s exactly why cooling tower makeup is such a strong end use:
- It creates consistent demand (so the cistern empties between rain events)
- It helps the harvesting system perform as functional green infrastructure
- It turns rooftop runoff into a utility resource instead of a stormwater burden
- It reduces potable consumption where the volume is meaningful
The takeaway
Not every building needs a multi-branch rainwater system feeding irrigation, toilets, and hose bibbs. Sometimes the best solution is the simplest one—pick the strongest end use and build a system that does that one job extremely well.
At 1020 Spring Street, rainwater harvesting is engineered to be a workhorse: capture rooftop runoff, filter it, and deliver it to cooling tower makeup using a durable concrete cistern, proven sediment filtration, and streamlined controls driven by a Yaskawa iQpump VFD.
It supports Atlanta’s stormwater management intent, reduces runoff burden, and can save hundreds of thousands of gallons of potable water over the life of the building—good for the owner, and good for community-wide conservation.
Preconstruction