Water consumption takes a hike in hot weather too

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It's not just the electric bill going up in the heat
June 22, 2017

When the heat cranks up, you know they’re coming:

Countless media reports about “peak power demand” and about the heroic steps our electric utilities are taking to supply uninterrupted power to keep those a/c units humming in crazy-hot weather.

Like this one: (link).  And this one: (link). And this one: (link).

Not to take anything away from our valued, public-serving colleagues in the power-supply biz, but… Hey! What about our local water managers? They have to meet a demand for water that often doubles when the temperature sizzles.

So, what are they? Soggy chopped liver?

As Warren Tenney, executive director of the Arizona Municipal Water Users Association, reported last August, municipal demand for water skyrockets in the Arizona summertime.

In February 2015, for example, the city of Peoria reported to the Department of Water Resources that it provided 423 million gallons of water to its combined commercial and residential customers. In July, Peoria's reported water demand spiked to 779 million gallons – nearly double the community’s February water usage.

The same pattern holds true for cities big and small. City of Mesa's reported water demand in December 2015 was nearly 1.9 billion gallons. Mesa customer usage was far higher, however, the previous July: 3 billion gallons.

The Valley’s largest municipal water provider, the city of Phoenix, experiences precisely the same challenges when temperatures soar.

While Phoenix has experienced a general decline in peak water-production levels in recent times – mostly due to customers converting from grass landscapes to xeriscape – June remains the city’s “hottest” month for water demand.

According to data provided by Phoenix Water Services, the annual average total water production each day for Phoenix is approximately 280 million gallons. In June that figure jumps to an average of 350 million gallons a day.

As you may imagine, though, when the temperatures begin approaching 120 degrees, as they have this week, water consumption races still higher. But largely thanks to those conservation efforts, the early days of the current week – the hottest days of this scorching week -- did not set records.

According to Phoenix Water Services figures, city water production on Tuesday, June 20 – the day temperatures hit 119 degrees at Phoenix International Sky Harbor Airport – production hit 402 million gallons. That amount was less than the highest annual production days for 2013-2016.

Preparing for such huge increases in daily water demand is complex for communities.

Phoenix Water, for example, orders its water supplies for the upcoming day 24 hours in advance, reports Water Department spokeswoman Stephanie Bracken.

Employees review reservoir levels from the prior day, and weather trends (consumption drops significantly when it rains) to determine how much water to order for treatment and distribution for the next day, she said.

Most Valley cities use a computer program called “Supervisory Control and Data Acquisition,” or SCADA, a system that allows communities to track water demand remotely and in real time.

“Operators use this innovative computer program to review water distribution continually throughout their service area and to track peaks in demands,” wrote Tenney of AMWUA. The SCADA system, he adds, has helped many Valley communities, including Mesa and Peoria track leaks. Like Phoenix, they have managed to keep water consumption mostly flat with the help of SCADA and other conservation efforts.

As with power generation, the key to community water systems delivering the goods 24/7 is infrastructure.

As temperatures soared this week, one small, privately owned water system in northern Arizona learned that reality the hard way when its customers lost service for several hours early Tuesday morning.

As reported by the system owners, there was no system “breakdown.” Demand in the summer heat simply had outstripped supply. Water hauled in by truck made up the difference until the system’s reservoirs were sufficiently refilled to meet demand.

Which goes a long way to explain why communities invest so heavily in infrastructure.

“Phoenix invests heavily in water infrastructure because just like power, clean water and reliable sewer services are vital to our community and economy,” said Kathryn Sorensen, the director of  Water Services for  Phoenix.