May 9, 2021

Professional Tool Reviews for Pros

Milwaukee M18 Switch Tank Interchangeable Sprayer System

The Milwaukee M18 Switch Tank Interchangeable Sprayer and Water Supply System starts with a power base and connects to tanks designed for water supply, pesticides, and concrete applications. It’s an intriguing concept powered by the M18 battery platform.

10-Second Summary

  • M18 battery operated power base
  • Three 4-gallon tanks available – water supply, pesticide, or concrete
  • 2820-21WS – Water supply Switch Tank system: $449 ($164 tank only)
  • 2820-21CS – Concrete sprayer: $449 ($164 tank only)
  • 2820-21PS – Pesticide sprayer: $399 ($149 tank only, $299 power base and tank)
  • XC 3.0 Ah battery will run up to 12 tanks on a charge

Milwaukee M18 Switch Tank Interchangeable Sprayer and Water Supply System

What’s interesting about this system is the two areas the system covers – concrete construction and landscaping. Both have legitimate uses and this is an interesting way to use one power base to expand in both industries.

The best part is that you’re looking at a battery-powered backpack sprayer. You can leave your days of manual pumping behind you.

Milwaukee M18 Switch Tank Interchangeable Sprayer System

This is a two-part system. The power base is where your battery connects and the motor lives. The tank assembly holds the pump, hose, accessories, and stores your liquid. It may seem odd to separate the motor and pump, but that’s what gives Milwaukee the ability to get different flow rates for different applications.

That kind of separation also means you can swap tanks without worrying about cross-contamination. As a mason, put different sealants in different tanks. As a landscaper, get a different tank for each pesticide and herbicide.

Each kit comes with a 3.0 Ah battery – enough for up to 12 tanks or 48 gallons of product. If you want more runtime, any Milwaukee M18 battery fits in the compartment, including the 12.0 Ah High Output.

Water Supply

For the construction side of things, the Milwaukee M18 Switch Tank Water Supply system is primarily targeting concrete cutting and drilling. It gives you adjustable pressure between 20 and 60 PSI with 5 adjustment settings.

The tank has a dual diaphragm pump and a wide mouth with a strainer.

Milwaukee M18 Switch Tank Interchangeable Sprayer System

  • Milwaukee 2820-21WS
  • 20 – 60 PSI with 5 adjustment settings
  • 0.16 – 1.13 GPM flow rate
  • Up to 12 tanks per charge with a 3.0 Ah battery
  • Nitrile seals
  • 10′ hose with quick connect
  • Water spray nozzle included
  • 18.45 pounds with battery, power base, and tank
  • 3-year power base warranty
  • 1-year tank assembly warranty
  • $449 ($164 tank only 49-16-28WS)

Concrete Sprayer

This one is for Pros working in concrete with a similar build as the Pesticide sprayer. You get the same 20 – 120 PSI adjustable pressure with 5 settings and 25-foot spray distance. The entire tank gets Viton seals.

The major difference is the flow rate. You’ll get 0.14 – 0.82 gallons per minute of flow from the concrete system compared to 0.10 – 0.51 from the pesticide sprayer.

Milwaukee M18 Switch Tank Interchangeable Sprayer System

  • Milwaukee 2820-21CS
  • 20 – 120 PSI with 5 adjustment settings
  • 0.14 – 0.82 GPM flow rate
  • 25′ spray distance
  • Up to 12 tanks per charge with a 3.0 Ah battery
  • Viton seals
  • 4′ hose with sprayer handle and wand
  • Lock off/on mechanism on sprayer handle
  • Large diameter adjustable nozzle and fan nozzle included
  • 18.3 pounds with battery, power base, and tank
  • 3-year power base warranty
  • 1-year tank assembly warranty
  • $449 ($164 tank only 49-16-28CS)

Pesticide Sprayer

The Milwaukee M18 Switch Tank Pesticide Sprayer system has 5 adjustable pressure settings from 20 to 120 PSI with a maximum spray distance of 25 feet. The lower flow rate is designed to give you more control for targeting small areas.


The tank has the same dual diaphragm pump as the others along with Viton seals in critical areas and nitrile seals in others. It also features a wide opening with a strainer.

  • Milwaukee 2820-21PS
  • 20 – 120 PSI with 5 adjustment settings
  • 0.10 – 0.51 GPM flow rate
  • 25′ spray distance
  • Up to 12 tanks per charge with a 3.0 Ah battery
  • Viton seals on critical areas, nitrile on others
  • 4′ hose with sprayer handle and wand
  • Lock off/on mechanism on sprayer handle
  • Small diameter adjustable nozzle and fan nozzle included
  • 18.3 pounds with battery, power base, and tank
  • 3-year power base warranty
  • 1-year tank assembly warranty
  • $399 ($149 tank only 49-16-28PS or $299 bare tool 2820-20PS)

Using the Milwaukee Switch Tank System


We’re primarily using the pesticide sprayer for our Switch Tank fun and the majority of our impressions are based on its use. The concrete sprayer is slightly different with its higher flow rate, but pretty much the same experience. The water supply is where delivery changes significantly. We haven’t yet had the chance to use it in that capacity.

With that said, it takes just a couple of minutes to get used to the power and flow rate adjustments. They’re really easy to reach and manipulate.

Once you fill the tank or swap tanks, the system may need to prime—something it does automatically.

Reviewer’s Note: Typically you always want to add chemicals to the water when they require dilution. With the Milwaukee Switch Tank, you eliminate the need for the typical “shaking the canister” dance you undergo with manual sprayers. Instead, just add the chemical to the filled switch tank and agitate it for a minute or so using the wand. You get a self-agitating system that saves you time…and your arms. When done, replace the cap.

Our pest control specialist used the Switch Tank as a sort of staging device. He could save time by simply grabbing the tank instead of dragging out the long hose. He even filled it directly from the larger tank, eliminating the need to deal with mixing chemicals.

Milwaukee Switch Tank pest control

After everything is properly mixed and ready, just find the flow rate that works for you and get to work!

Having a 25′ range for the sprayer is great for treating anything up in trees. The system easily reaches the soffits of taller residential buildings, and it quickly and easily covered large ground areas.

Switching Tanks

This would be an incomplete Milwaukee Switch Tank review if we didn’t actually talk about switching the tanks! It’s a pretty simple process. A clip on the front and one on the back secure the tank. Once those are loose, the tank just lifts up and off.

Two downward facing tabs on the back of each tank slip onto the harness frame and hold it in position while you lock the clamps back down.

While you have the tank off, notice the 3 metal connections—two silver and one gold. Keep an eye on these and wipe them clean from time to time. If your pump isn’t working and you know you have a good battery, one of these connections likely needs cleaning.


Manual backpack sprayers range from 7–12 pounds. You will notice the extra 6 pounds of weight that comes with this system—more once you add 4 gallons of liquid (approximately 32 pounds).

The harness holds the tank close to your back. It does a nice job of balancing the weight and gives you plenty of adjustability. I didn’t have any issues getting a good fit for my 6′ 2″ frame.

The straps include some padding, but it could stand to have more around your shoulders. It’s a little uncomfortable there but certainly better than most backpack sprayers I’ve used. The hip straps seem to carry the weight well.

One thing Brian, our resident pest control expert enjoyed about the system was how easy it came apart for storage. He was able to set the tank upright in the very back of his truck and store the base and harness toward the front.

Milwaukee Switch Tank portability

Wand Storage

The most obvious place to store the wand is in the center of the tank handle. You also get a side storage position against the frame handle with a point directly below it to hold the tip.

Those are great, but it takes some practice to put the wand back in either location while wearing the Milwaukee Switch Tank. If you look closely at the hip strap on your right, an elastic loop lets you run the wand through it like a holster. This works well when you have a lot of distance to cover and want to free up your hands.

The wand is often a point of concern. You can bend or break cheap ones easily. While it’s definitely possible to break the ones Milwaukee provides, they seem pretty stout. They even include a lock on and a lock off on the handle.

We Shouldn’t Have to Say It, But We’re Gonna

Only use the Milwaukee Switch Tank for the chemicals it’s rated for. Each tank is specifically designed for the environment and job they say. The different tanks have different seals based on the expected chemicals to be used. Bleach is out. Flammable liquids are out (you have a battery for a power source). Margaritas are out…wait, or are they? In any case, you also want to make sure to thoroughly rinse out the tank before adding any new chemicals to avoid cross-contamination or potential reactions.

It’s pretty clear that Milwaukee put some thought into creating a tough design. Just remember that they want you to get the most life and value out of this tool.

This article originally posted on January 17, 2019. It’s been updated with our first-hand experience.

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It’s not spraying for me? Highest setting. It’s making noise but seems as though something is stuck because not coming out correctly. I lieterally just got the darn thing.

Blaize Holland

Adam Britt

Jérémy Marchesan

Anthony Marchesan

William Hague

Christopher Clarry


I think their is a mis-type in the 3rd paragraph. The motor & the pump are essentially the same. I think you meant “separate the motor/pump & THE TANK.” It’s way over priced for the pesticide/herbicide/foliar feed application farmer or person. I could buy 3 Ryobi’s, for $50 more than the kit of this, and I still won’t be able to isolate my sprays with the Milwaukee until I fork another $150 over. I was so happy to see this come out, and immediately saddened after seeing the price. I love my red tools, but looks like I’m sticking with… Read more »

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