Data Center Water Use vs. Landscape Irrigation Waste: The Bigger Fix

By Jon Peters, General Manager, Irrigation Managers · 33+ years in irrigation and agronomy

Every time a new data center is announced, water becomes one of the loudest flashpoints in the conversation. How much will the facility use. Whether it is fair to the people living nearby. Those questions are worth asking. They also tend to focus on one number and miss a much bigger picture.

This is not a defense of data centers.

Data centers are large industrial users of water and electricity. The conversation about that use is legitimate. The point here is different. The data center is not the only major water user in any region, and in many cases, it is not even the largest one. If we are going to make headlines about millions of gallons going into a data center, the same energy belongs on the millions of gallons misapplied or lost to leaks and runoff from lawns, parks, and medians every season for no benefit at all. Both conversations are worth having. Right now, only one of them is getting the attention.

Start with one fact.

The total volume of water on Earth is fixed. We will never have more. We will never have less. Water falls as rain, soaks in, runs off, evaporates, and the cycle goes on. The water itself is not the problem. The problem is the location, quality, and reliable availability of that water compared to the demand.

Water and electricity are coupled.

When water has to get from where it is to where someone needs it, electricity does the work. Pumps lift it from the ground. Pressure stations push it through pipes. Treatment plants clean it. Cooling systems cycle it. All on the grid. Water that gets moved for no useful return costs both gallons and kilowatt-hours.

The water leaving a data center is still water.

Roughly 80 percent of the water a typical data center uses for cooling evaporates and goes back into the cycle directly. The other 20 percent leaves as wastewater. Some facilities already reclaim that wastewater onsite. The technology to capture cooling discharge and put it back to work for irrigation, landscape support, or non-potable plant use is well established. Letting cooling water go to waste is a choice, not a constraint.

Run the math.

A medium-sized data center uses around 110 million gallons of water a year for cooling. A hyperscale facility can pull up to 1.8 billion gallons a year (Lawrence Berkeley National Laboratory).

By the EPA working figure that as much as 50 percent of outdoor water in the United States is excess to what plants need, a typical warm-climate lawn loses 15,000 to 25,000 gallons every year. A neighborhood of 1,000 homes: 15 to 25 million gallons of excess irrigation annually. Multiply across the hundreds of HOA parks, school grounds, cemeteries, corporate campuses, and commercial properties in a single metro area, and the recoverable irrigation loss inside a few miles of a typical new data center site is often comparable to, or larger than, the facility’s annual draw.

That number is not in the headlines. It is in the yards, the parks, the medians, and the campuses. And the technology to fix it is already on the shelf.

Wasted irrigation, defined.

Wasted irrigation is water that was delivered to the landscape and the plants never used. It comes from two sources: applying more water than the soil can hold within the root zone, or applying water when the soil cannot hold it. Excess water returns to the cycle either way. The energy and treatment that put it there did no useful work, and less water is left available for other users in the area.

The available move.

Fighting change is easy. Fighting the data center is satisfying for a news cycle. The data center will be built somewhere. As we said, the volume of water on the planet is fixed, but the volume available for use in any given area is finite, and so is the electricity grid. When we step back and look at the bigger picture in each watershed, all water use matters, and there is one move that no one talks about.

Dialing down the volume of water delivered to landscapes to match what the plants actually need has the potential to reduce overall demand enough to accommodate users like data centers. It starts with calculating plant demand and managing water application to match. Monitor for waste. Track reductions in gallons. That work alone reclaims more water than most of the data centers being argued over.

Second, treat the cooling discharge from new data centers as an irrigation feedstock, not a wastewater problem. With the right treatment, the same water that leaves the cooling system can irrigate a community park, a school field, or a campus lawn. Two recoveries from one play. The technology is already in service at some data centers.

The point.

Same amount of water on this planet, always. Different demands on it every year. The conversation about a new data center’s gallons per day is going to happen. It is worth pairing with the math sitting in plain sight on every irrigated property within a few miles. Reducing the irrigation loss recovers water. Recovering data center discharge for irrigation recovers it again. Same water. Better use.

Thinking outside the box: maybe the companies building data centers should be asked to help provide education and tools to bring irrigation water use efficiency to the areas they are impacting.