Just like the greenery which grows so profusely and the sweeping beaches that line the coast, it’s hard to picture Florida in your mind’s eye without conjuring up images of vast expanses of water which are picture-perfect and designed for swimming, fishing and water skiing. In fact, there are approximately 7,800 natural lakes in Florida with a surface area of one acre or more. To add to the profusion, the people who call Florida home go out of their way to create manmade lakes of every shape and size and these are often to be found supplying irrigation water to housing communities and other places people want the landscaping to look great – like shopping malls, sports grounds and golf courses.
The most spectacular example of the creation of manmade watering holes was probably unveiled in April 2018, when the first ever manmade lagoon in the country was officially declared open in Wesley Chapel, near Tampa. Despite covering more than 7.5 acres and offering visitors the chance to swim, sail or paddleboard, the lagoon, according to its owners, holds 16 million gallons yet still uses less water than an 18 hole golf course.
Meanwhile, and on a smaller scale, the aptly named town of Miami Lakes contains no fewer than 32 lakes, every one of which was created by people rather than Mother Nature and it’s difficult – if not impossible – to find a gated community in Florida which doesn’t boast at least one sizeable manmade body of water. Lakes of this kind are designed to offer idyllic views, a haven for some of the local wildlife and a natural form of flood defense. With the right system installed they can also provide a rich source of irrigation for the local greenery.
People have been pumping water from lakes for irrigation since as long ago as 250 BC. Back then, in ancient Greece and Rome, a device called the Archimedes screw was employed to shift the water. Shaped, as you can probably guess, like a giant screw, it was a device which, when turned by hand, lifted water along the inside of the screw to deposit it out of the top. It’s a principle which is still used in some water management applications today, but back then it needed at least two people to operate and was slow-moving and primitive when compared to today’s smart irrigation systems and improved irrigation water delivery solutions - from complete irrigation pump stations to booster pump systems, lake transfer pumps, lake recharge pumps and more.
The development of these mechanized irrigation systems was kick-started in earnest in 1928 when a man named Armais Arutunoff invented the world’s first submersible pump in Los Angeles. Although the pump was intended to shift oil rather than water, it established many of the principles behind modern submersible pumps, being a unit consisting of a motor and a pump, both of which could be completely submerged in liquid.
Submersible Pumps Come With Advantages
In the case of irrigation today, the liquid in question is water, but the submersible pump does the same job, pushing the water toward the surface of a lake or well using the pressure created by the water itself, rather than pulling it as other types of pump – such as a jet pump – are designed to do. The operation of the submersible pump makes it more efficient than many other types of pump, but that doesn’t mean that the pumps come without any issues. Before examining the possible problems that a submersible pump might present – and offering solutions - it’s worth looking at some of the advantages of the system.
The aforementioned efficiency of a submersible pump is one its major advantages. When installed correctly it will use less power than other forms of pump and will therefore be cheaper to run. In addition to this, submersible pumps can push the water further from the lake itself and higher above the surface level, making them the ideal choice for more extensive irrigation systems based on multiple sprinklers over a large area.
The type of submersible pump used to shift water in this way is often an oil-filled pump. The oil encases the working parts of the pump, protecting them from any ingress from water and also helping to keep the unit cool during prolonged operation. The watertight nature of the design ensures that the electrical components of the pump are protected from the risk of shorting when submerged, and a pump of this kind also offers the advantage of being self-primed, as opposed to other types of pump which need to be primed when starting.
Possible Problems with Submersible Pumps
Historically, pumps have been submerged under the surface of lakes in order to deal with the issue of noise, but any reduction in operating volume came at the expense of the equipment itself wearing out more quickly due to its horizontal operation. In addition to this, the pumps would be difficult to access when they needed repairs or servicing, requiring the expertise of a diver to go down into the lake - or the power of a crane to lift the pump to the surface. Legacy systems can still be found featuring an intake below the surface of the lake and the pumps and motors themselves enclosed in metal boxes above the surface, something which runs in contradiction to many of the principles of pumping water and is highly likely to lead to a highly inefficient irrigation system.
One possible issue arising from the use of a submersible pump is that problems such as ruptures or a leaking gasket could be hard to spot due to the submerged nature of the unit. If the pump is part of a smart irrigation system, the variation in the pressure and amount of water being pumped caused by any mechanical failure of the pump would be picked up immediately by the system itself. However, this does still leave the issue of accessing the part of the system which needs to be repaired.
A check for leaks in places such as sprinkler heads or sprinkler valve boxes would help to eliminate issues with the land-based part of the system. Any problems with the submersible pump would have to be identified and dealt with immediately by trained technicians. The pump itself, because it's submerged beneath the surface of the water, may take on debris such as vegetation, silt and animal waste present in the water. Even in very small amounts, debris of this kind could build up enough to clog the pump itself or, further down the line, block the water pipe or the heads of the sprinklers being used.
The shield placed in front of the intake will be able to filter out larger items of debris, but contrary to its name, it really acts more like a guard than a full-scale filtration system. In addition to the impact of debris present in water, some submersible pumps have to deal with water which has naturally high levels of calcium. This will lead to deposits building up to such a degree that the pump eventually becomes blocked and can’t draw enough water to stay cool. Just as negative can be the effect on a pump of being placed in brackish water, which contains higher levels of salt than freshwater, and which will corrode any submerged components of a pump even if they are constructed from stainless steel.
Using a Submersible Pump in a Well
A well could be a viable – sometimes preferable - alternative to placing a submersible pump in a lake. Pumping water from a lake or from a well is a choice which is often dictated by the location of the irrigation system and the practicality of each option. A well might only be a workable option if the well in question fills from a replenishable source without adversely impacting the water table or the surrounding landscape. For that reason, the installation of a submersible pump will begin with testing the well itself, which is a recognition of the fact that two wells dug just a few hundred yards apart could deliver very different amounts of water. The static level of the water will be noted and the pump will be run for an hour to determine whether, for example, running at 300 gallons per minute causes the static level of the water to drop by 30ft or 10ft. This is a vital test because if a submerged pump is installed when a well just about delivers sufficient water, a subsequent period of drought could see the static level drop and the pump and motor exposed, which would cause them to burn out.
The solution to this – in addition to not installing a submersible pump in a well which is likely to run dry – needs a more holistic approach and might include for example, the use of centrifugal pumps and the implementation of smart systems like Hoover’s Flowguard technology which will pick up on the absence of water and shut the pump down before expensive damage can occur.
Further Studies
A study published by North Dakota State University, and last reviewed in 2022, looked in depth at the types of pump which might be selected for a large scale irrigation system, rating types of pump against a range of factors including the following:
- The source of the water
- The pumping flow rate demanded by the system
- The total suction head
- The total dynamic head
As well as providing complex formulae for calculating the amount of power required to run a pump, the study explained the ‘pump curve’, the name commonly given to the graph which is created in order to illustrate the efficiency of a pump’s performance under a range of circumstances. Read correctly, a pump curve of this kind can be used to select a pump for a specific location and size and type of irrigation system. In addition to these general points, the report breaks down the advantages and disadvantages of a number of different pump types, including submersible, centrifugal, vertical turbine and propeller. The advantages and disadvantages of a submersible pump, as highlighted in this study, are as follows:
Advantages Highlighted
- Submersible pumps can be used in deep wells
- Submersible pumps do not require priming
- Submersible pumps can be used in crooked wells
- Submersible pumps are relatively easy to install
Disadvantages Highlighted
- Submersible pumps are more expensive in larger sizes than deep-well vertical turbines
- Submersible pumps can only be driven by electric power
- Submersible pumps are more susceptible to lightning strikes
- In order to operate, submersible pumps require water movement past the motor
Solar Power and Submersible Pumps
When the topic of submersible pumps is raised one of the issues cited in their favor is often the fact that they run more efficiently, and so require less power to operate than many other types of pump. This is important for two reasons. The first is clearly the issue of cost, and the annual power bill for pumping water around a large scale irrigation system. This is something which is already bound to be at the forefront of the thinking of anyone questioning which type of irrigation pump would be best suited to their system.
What might not be quite as widespread is an awareness of the increasing role which solar power now plays in running irrigation pumps in various parts of the world. In our regular H2O Zone news digest we round up stories from across Florida (and sometimes beyond) which relate to the topics of sustainability and conservation.
Solar power as an option for powering a submersible pump is something which might be worth considering not just for the money it will possibly save, but also as a means of helping to burnish the eco-credentials of the organization in question. Whether this is a business, a retail outlet, a sporting franchise or residential development, being able to point to a practical demonstration of a commitment to sustainability could play a huge role in helping to attract the next generation of consumers.
A paper published by Nature.com in 2023 looked at the reliability and performance of an underground water pumping system running on solar power. The study explains how a system of this kind can be used in two ways – it can pump during sunlight hours and store water in tanks to be used if and when the sun isn’t shining, or it can store electrical energy in batteries during daylight and use the power later. The general conclusion of the study, based around an irrigation system in Egypt, was that solar powered irrigation systems would operate efficiently and reliably, but that factors such as the surface temperature of the solar panels and the efficient operation of the inverter used to convert the DC power produced by the solar panels to the AC power needed to drive the pump motor would need to be factored into the design of the system.
A report published by the World Bank in 2024 found that solar powered irrigation systems of this kind helped to improve food production, food security and livelihoods in places such as South Asia and Sub-Saharan Africa. While the infrastructure needed to drive an irrigation system is much more likely to be up to the job in a part of the world like Florida, there is still every chance that a switch to some degree of solar power for submersible pumps – even if only as a back-up or adjunct to electricity or other types of fuel – is going to become an increasingly attractive proposition.
Centrifugal Pumps - a Modern Solution With Advantages For Florida’s Irrigation Lakes
The modern solution is to utilize centrifugal pumps above the surface, which can draw the water from a lake if that is the source which has to be used, and which are much simpler to install and access for repair and service purposes than the submersible alternatives.
Many irrigation solutions we devise benefit hugely from the use of centrifugal pumps, mitigating the issues surrounding submersible pumps. But whatever our recommendation for a project, we’ll ensure from the outset that both the design and installation of an irrigation system have first of all taken into account all of the relevant factors, from whether placing a submersible pump in a well is an option, to analyzing the water in any manmade lake which has to be used.
Analysis of the water will determine how many filters, if any, will need to be fitted, and will take account of geographical aspects such as the fact that lakes on the west coast of Florida are likely to have more species growing within the water, like bryozoa, aquatic invertebrate animals which are only 0.5 millimeters long and will have to be filtered from the system. Expertise like this is every bit as valuable as the most advanced equipment and the best engineering.
