Focusing Irrigation Conservation Programs to Maximize Savings

By Mackenzie Boyer

Want to know how much potential a water utility customer has to conserve irrigation? First you need to know how much water they’re using. What about figuring this out for every customer in a utility? You’ll want to check out our recently published article “Mining for Water: Using Billing Data to Characterize Residential Irrigation Demand.” 

Treasure Trove

A utility’s monthly water billing records can hold a wealth of information - a gold mine, we would say. The monthly records, even when water meters measure only indoor and irrigation water combined, can provide a great insight into irrigation behavior of individual customers. And if the utility also has parcel identification data linked to their billing records? Jackpot. 

Research area

Tampa Bay Water just happened to have some very detailed, very comprehensive billing data for their six member governments (Pasco County, New Port Richey, Pinellas County, St. Petersburg, Hillsborough County, and Tampa). Our analysis of their data used over 30 million monthly billing records of over 165,000 customers - comprehensive, to say the least. The monthly total water use (indoor and outdoor combined) and parcel data were used to estimate each customer’s monthly irrigation demand (what we estimate customers actually used for irrigation). Each customer’s monthly gross irrigation required (GIR, what we estimate a landscape actually needed to be well-watered) was estimated using parcel, weather, and soil data.

Managing and manipulating the data required some heavy computing power. The statistical programs SAS and R were used, with R selected specifically to run a series of 875,000 calculations at UF’s High Capacity Computing Center. (It still took the computing center over a week to run all the equations.) ArcGIS was used to map customer locations and determine their site-specific weather and soil conditions. We grouped customers by their irrigation habits by comparing their demand to GIR (how much they irrigated compared to how much their landscape needed). Our groups were: high, medium, low and occasional irrigators.

Stay the Course

We found that many, many customers in the Tampa Bay region do not regularly irrigate (our occasional irrigator group). For this 85% of customers, the old adage “If it isn’t broken, don’t fix it” holds true. These customers should not be actively recruited for conservation programs because we don’t want to inadvertently increase their irrigation by recommending irrigation practices that use more water than their current practices.

Each occasional irrigator did not irrigate much, but the group was so large that the occasional irrigators were responsible for 51% of irrigation utility-wide. In contrast, only 2% of customers were classified as high users, and these customers were responsible for 9% of the irrigation demand.

Keys to Success

Successful irrigation conservation programs are far from one size fits all. Conservation programs should be targeted to the high user customers to maximize the water savings potential. Utilities often have the tools in their historical monthly billing records (even without the comprehensive data of Tampa Bay Water) to estimate how much irrigation customers use. Using this knowledge, they can direct conservation efforts to those who could benefit the most.

Smarten Up for 2017: A SWAT Training in Southwest Florida

Last week the Dukes research group conducted its third smart irrigation technology training of 2016. This collaboration with Tampa Bay Water and Florida Irrigation Society packed the Brooker Creek Preserve’s auditorium with area contractors, municipal reps, Extension faculty and local water management district staff eager to learn about water-saving technology.  

Best Practices

Following proper design and regular system maintenance, irrigation best practices also include using smart water application technology to avoid unnecessary irrigation. 

Next week: FL Irrigation Society & @TampaBayWater collab to train on smart water tech: https://t.co/O3JJFGrhDa pic.twitter.com/Q37ztuvtQq

— UF/IFAS IrriGator (@IrriGatorUF) November 2, 2016

During the training, presenters covered types of smart technology and proper installation and programming. They also drew lessons from recent field experiences to underscore the importance of correct wiring to maximize device effectiveness.

Hands-on station with water-use expert Bernard Cardenas (courtesy: Dave Bracciano)

Frank Galdo explains it all

Guest presenter Frank Galdo of Pasco County Utilities (pictured above) stepped in during the latter section to discuss how two types of sensors (rain and soil moisture) can be used on one irrigation timer – a scenario his team encountered and diagnosed this summer.

In the Clouds

Seven vendors were also in attendance last week. Despite the growing popularity of the cloud-based irrigation timer sector, trainers kept the focus on soil moisture sensor and weather-based irrigation controller basics.

Fresh from Denver: team Rachio talks cloud-based tech

Vendors, however, had plenty to present on their unique interpretations of cloud-based irrigation technology – which allows for WiFi-enabled weather-based programming as well as remote access to your timer from any mobile device.

...without whom none of this would be possible

Looking Ahead

For anyone attending this year’s Irrigation Show and Education Conference (next month in Las Vegas), you know that smart water technology is continually improving. And the Dukes research team will continue to train irrigation professionals throughout Florida on these proven water-saving devices. See you in the new year!

One Water Saving Sensor Too Many? - A Dialogue

By Michael Gutierrez

Over the summer an area utility came to us with a technology problem. Due to an incentive-based program, soil moisture sensors were being installed on new housing development irrigation systems. This is just the kind of best practice we love to hear about. In this instance, however, the installers elected to add rain sensors as well. Wiring issues ensued.

This month the Dukes research group is conducting its 3^rd smart water technology workshop of 2016. To mark the occasion, water-use expert Dr. Michael Dukes agreed to a discussion on the above “two sensors” situation so we can all better understand the installers’ intentions and what went wrong. This is also a preview of some of the topics that will be addressed in next week’s training.  

Dr. Michael Dukes instructs during a smart water technology training earlier this year

MG: Rain sensors v. soil moisture sensors – which is more effective?

MD: Soil moisture sensors are definitely more effective than rain sensors. We’ve shown that time and time again. They’ll reduce irrigation two to three times more under the same conditions. And longevity is better in soil moisture sensors. Despite this, rain sensors have been around for a long time and they are in everyone’s way of thinking – everyone being contractors, practitioners, utility people. To us, being close to the research it makes sense just to use a soil moisture sensor. “Why would you consider a rain sensor based on all this research?” Well, for practitioners one of the things that is on top of their mind is seeing an irrigation system run when it’s raining. A rain sensor would stop that. Their next thought is “why not add a soil moisture sensor. Wouldn’t my results be even better?”

A soil moisture sensor properly installed in an undisturbed soil profile

MG: As people that specialize in encouraging best practices, we like seeing practitioners install water saving devices. In reality, one well-installed, functioning device on a system is a rare thing. Two devices is something I’m still trying to wrap my mind around.

MD: In this instance, the only reason is to get the instant shut-off that a rain sensor would provide during a rainfall event. But think about it this way: we only have a limited amount of research on testing a soil moisture sensor with a rain sensor together and in that limited study there was a benefit. It wasn’t a great deal, but there was a benefit. But think about the conditions where you get a benefit: there has to be irrigation during a rain event and if you only have several irrigation events scheduled per week that means everything has to line up perfectly. I’m not sure how likely that is. The benefits to adding a rain sensor is probably marginal because we already know they require more maintenance. You’re adding something that needs more maintenance for some perceived benefit which is not all that great.

Rain sensor: going the extra mile and getting it right

MG: This is what I was thinking. Installers may not be so familiar with the research, but they know rain sensors. What it’s like to work with these devices. Why…

MD: There’s another angle on this though: the soil sensor technology we’re discussing in this instance is slower in reacting to moisture. So the addition of a rain sensor may actually help address this. It’s not a terrible idea.

MG: So intentionally or not, installers in this instance may have compensated for a short-coming of one device by adding another.

MD: That’s exactly right.

MG: I just stumble on the idea of willingly pairing two devices, when you know one will deteriorate before the other.

MD: Perception is reality. Perception is a big deal. We’re in the process of publishing a paper on the OCU research. And surveying homeowners participating in that study, their perception of water savings was more important than the actual water savings in their attitude of whether they were going to continue using smart irrigation technology in the future.

The Orange County Utilities (OCU) study also includes weather-based irrigation controllers (WBICs)

MD: The important part here is: having a rain sensor to prevent a system from running when it’s raining, that goes a lot toward perception. Having a system with only a soil moisture sensor is probably not a real problem in the long run, day in and day out over the year. But let’s say a developer sees a system watering in the rain one time. That may mean the difference between these new homes continuing to get this technology or not getting it.

MG: The only reason we’re actually aware of this "two sensors on one timer" practice is that something went wrong. Can you talk about this?

MD: What happened was the timers in this instance have a rain sensor port and the installers wired both sensors to that port. They intended an either/or scenario to interrupt irrigation. But when both are wired in this way they are in parallel, so both have to trigger to interrupt irrigation. They needed to be wired in series, so either/or would break the circuit.

When the soil moisture sensor can wire into the rain sensor port, a series connection is necessary (courtesy: Francis Galdo)

MG: In summary, if you insist on using two devices – rain sensor and soil moisture sensor – with your timer….

MD: Know your wiring.

Catch the Dukes research group in Tarpon Springs next week for more in depth insight