Misting System Basics

misting system cooling down a patio in the evening

"Misting System" describes a whole range of outdoor cooling methods that use a fine spray of water to cool you, your family, your guests, your customers, your workers, teammates, employees… even your animals -- pets or livestock.

These systems are known by a number of terms including "Fogging Systems" or "Spray Cooling".

But every one of them fits in the category of Misters, and every one of them works the same way.

How a Misting System Works

All misters work with evaporative cooling - the natural cooling effect that happens when water evaporates in warm air. They all work beautifully in dry weather. Some can work beautifully in humid weather, but not all, so do your homework here before you buy one for a humid area. See especially the next section on When and Where to Use a Misting System.

misting system cooling the patio of a luxury villa

They can all reduce dust and odors in the area, as well as static electricity and the presence of flying insects. They can even help regulate humidity so are terrific for plants --greenhouses, atriums, courtyards, etc. And they can cool you without getting you wet. There are some that can get you wet, though.

Water is forced through very small nozzles to create a fine mist or a very, very fine fog. As the droplets of water evaporate they cool the air immediately around them. The finer the mist the more thoroughly it evaporates, cooling you off more than a coarser mist. And the finer the mist, the closer you can get to the nozzle without getting wet.

The terms "mister" and "fogger" are often used interchangeably so there is much confusion about which is which. Some misters create a spray made of larger droplets that can get you wet. These are usually systems that use low or medium water pressures and larger spray nozzles. But foggers use high water pressure and tiny spray nozzles to create a fog-like mist that evaporates before it has a chance to get anything wet.

Higher pressure systems are often called "fog" systems because the droplets are so small they float on the air like a fog.

Water Pressure is the Key

All foggers are a kind of misting system, but not all misting systems are foggers. To avoid this confusion it helps to think in terms of the water pressure -- Low, Medium, or High. Thinking in terms of the water pressure they use is a more precise way to categorize these systems because the water pressure is the main indicator of a misting system's performance.

Water pressure is commonly measured in PSI (pounds per square inch) or BAR.
1 bar = 14.7 psi. 1 psi = .0689 bar.

A Low Pressure system is almost like being near a sprinkler. It can cool you quite a bit, and you might get a little bit wet. For a casual group that laughs at a sprinkling of water, these simple systems are great -- the simplest and least expensive of all. The only ones that don't use electricity. They work with gravity-fed water pressures which are the easiest to come by and the most common -- gravity-fed pressures of about 20 - 120 psi / 1 - 8 bar are in the range provided by most local water utilities. Their spray cools a small area, so you'll need to be near the nozzles to get cool. But the closer you are to the nozzles, the more wet you'll get.

One of the most popular brands of low pressure systems is MistyMate. Their pre-assembled systems are affordable and easy to install. Some of their sytems make use of a pump, which puts those in the range of Medium Pressure systems.

A Medium Pressure system uses a motorized pump to raise the pressure to 100 - 250 psi / 7 - 17 bar. The pump and motor, tubes, fittings and nozzles are all rated to work within this range. The spray is fine enough to cool you in hot dry weather, is less likely to get you wet and can provide more cooling than a Low pressure system, and is available is a range of prices. A low-power 160 psi / 11 bar pump is often called a "booster pump".

A High Pressure system will give you the maximum cooling of any misting system -- even in areas with high humidity -- without getting anything wet. High pressure, by default is anything over 250 psi / 17 bar. But these systems usually range much higher -- in the neighborhood of 800 - 1200 psi / 55 - 83 bar. As with all mist systems, all components must be rated to work within the same range of water pressure.

Medium and High Pressure systems use pumps to increase the water pressure from any water source -- a gravity-fed source that already has some water pressure, or a ground source such as a pond or tank with still water that has no pressure.

The higher the resulting pressure, the cooler -- and drier -- you'll feel.

When & Where to Use a Misting System

The drier the air, the more completely water can evaporate, so the greater the cooling effect. A misting system will indeed cool you off in dry heat or humid heat; but the drier the air the cooler it will feel. And the more humidity in the air, the finer the mist required to achieve a sense of cooling. The more humid the air, the higher the water pressure and the smaller the nozzle opening you'll need in order to feel a cooling effect.

Following are some typical temperature reductions you can expect with a High pressure system:

  • as much as 10° F / 5.5°C in areas with humidity above 80%
    Rio de Janeiro, Brazil; Bangkok, Thailand; Darjeeling, India; Darwin, Australia
  • as much as 20°F / 11°C in areas with humidity between 40% and 80%
    Orlando, FL, USA; Sydney, Australia; Vancouver, Canada; London, England
  • as much as 30°F / 16.5°C or more in areas with humidity below 40%
    Las Vegas, NV, USA; Cairo, Egypt; Abadan, Iran; Baghdad, Iraq

Since humidity DOES affect the cooling effectiveness of a mister, it may not be the best outdoor cooling method for your circumstances. Take a look at our comparison page, or our pages on other outdoor cooling methods to make an informed decision. We have a page for outdoor fans, which are extremely effective in very humid weather. Swamp coolers use evaporative cooling in an enclosed unit. Even portable air conditioners or simple outdoor shades may be a better solution for your needs, or consider combining cooling methods. You may be surprised by what's possible.

Cooling an outdoor area can be tricky if you don't understand which cooling method to use and how to use it. Most people don't even think of cooling off an open area in their yard, their outdoor business areas, a construction site, or even a field. But misters can be very effective for cooling open outdoor areas because the weight of the water in the spray keeps the cooling relatively confined. That means the cooling effect will stay in the area you actually want to be cooled. So you can take your misting system where you need it most -- How about the park? the beach? Camping? A booth at the fair? Portable systems really open up the possibilities!

a misting system used on the field to cool down a sports team

What Makes a Great Misting System

There are few, if any standards for a misting system. Anyone can set up a garden sprinkler and call it a mister. But a great system has a balance of elements. The technical elements are outlined and discussed in our series, The 3 Parts of a Misting System. The first in that series starts with misting systempumps. Note that these technical elements by themselves don't make a GREAT system. A misting system isn't great unless it meets YOUR needs.

A system with all of the highest quality, highest powered, most expensive elements may actually be great in many situations. But if you have a small patio in an apartment in a quiet neighborhood, this same system will likely be too noisy, too expensive, and in short, too much for you … NOT a GREAT system … FOR YOU.

Is it portable? And if so, do you really need a high powered system for your kids' sports team? Maybe a smaller, lighter, less expensive system that gets the kids barely wet is exactly what YOU want. But that doesn't mean it's great for someone else's elegant wedding reception for 200 guests.

Once you have an overall understanding of how a mist system works and what makes a good system, you'll be able to make some knowledgeable comparisons. Not only with other mist systems, but with other outdoor cooling methods. Then you can decide which is the best of all methods, or best combination of methods for you. Because however good the system may be, what makes it a GREAT system is if it meets YOUR standards.

Interested in learning even more?

  • To learn more about how evaporative cooling works, see our page on evaporative coolers.
  • To compare misting systems with other outdoor coolinsg solutions, visit our

    comparison page.

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