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Model #MS-401

Store SKU #1000025872

4 Gal. Diaphragm Backpack Sprayer

  • Designed to fit comfortably on your back for easy carrying
  • Handle designed for comfortable use with the right or left hand
  • Heavy-duty construction withstands exposure to chemicals
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Product Overview

Featuring heavy-duty, padded shoulder straps to help provide comfortable carrying, the ECHO 4 Gal. Diaphragm-Pump Backpack Sprayer is designed to use with powders, liquids and water-soluble solutions. Four nozzles offer stream adjustment for customizable spraying. The wand can be used for left- and right-handed applications.
  • Professional grade diaphragm pump equipped with Viton seals to withstand harsh chemicals, this pump is designed for use with powders, water-soluble solutions and liquids
  • Professional grade fiberglass wand and industrial grade flow control with comfort grip
  • Extra-large tank opening with handle integrated into the tank cap
  • Heavy-duty padded straps with waist belt
  • Ambidextrous folding pump lever and guard bar for stability
  • California residents

Additional Resources

From the Manufacturer

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4 Gal. Diaphragm Backpack Sprayer
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BrandECHOField KingScottsChapin
Name4 Gal. Diaphragm Backpack Sprayer4 Gal. Professional No Leak Backpack Sprayer4 Gal. No-Leak Professional Backpack Sprayer4 Gal. Self-Cleaning Backpack Sprayer with Hand Sprayer Combo
/box $130.99
Save $28.99 (22%)
Capacity (gallons)4444
Compatible WithBleach,Chemical,De-icing,Disinfectant,Fungicide,Grass Killer,Pesticide,Weed KillerFungicide,Grass Killer,Weed KillerFungicide,Grass Killer,Pesticide,Weed KillerChemical,Fungicide,Grass Killer,Pesticide,Weed Killer
Sprayer FeaturesAdjustable Spray Tip,Shoulder StrapAdjustable Spray Tip,Backpack,Shoulder StrapAdjustable Spray Tip,Backpack,Shoulder StrapAdjustable Spray Tip,Backpack,Shoulder Strap
IncludesSprayer OnlySprayer OnlyDual Cone NozzleSprayer Only
Hose length (in.)48 in50 in48 in48 in
Applicator typeSprayer/MisterSprayer/MisterSprayer/MisterSprayer/Mister
Product Length (in.)99.515.2514.75 in
Product Width (in.)14.51599 in
View ProductView ProductView ProductView Product



Hose length (in.)
48 in
Product Depth (in.)
Product Height (in.)
Product Length (in.)
Product Width (in.)


Adjustable spray tip
Applicator type
Capacity (gallons)
Compatible With
Bleach,Chemical,De-icing,Disinfectant,Fungicide,Grass Killer,Pesticide,Weed Killer
Sprayer Only
Shoulder strap
Sprayer Features
Adjustable Spray Tip,Shoulder Strap
Sprayer/mister type
Tank Material
HDPE (High Density Polyethylene)

Questions & Answers

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Customer Reviews

  • 3.9
    out of 483 reviews
  • 72%recommend this product
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Showing 1-10 of 483 reviews
This is one of the better back pack sprayers which I have every used, I recently purchased and r...
This is one of the better back pack sprayers which I have every used, I recently purchased and returned the 200 series as that sprayer has a piston which you need to do full arm strokes to pump it up. With the 400 series Diaphragm sprayer, you only need to move the handle a few inches and after a just a few pumps you're able to spray with force. This unit comes with 4 different spraying heads. I used the fan head sprayer which covers a nice area. The adjustable spray head allows you to spray in a dome shape or a stream. The steam goes a long distance. Overall for the price this is a great deal!
  • Verified Purchase
  • Recommended
The pump arm has two positions. Vertical for storage and horizontal for usage. Even though the pu...
The pump arm has two positions. Vertical for storage and horizontal for usage. Even though the pump stroke has a very short throw it is very difficult because of the angle of the pump arm. Even if I adjusted the straps for the pump to be in the highest position possible, it was still awkward for me to be able to push the pump handle completely down. I returned the sprayer.
Response from HDX Customer CareJul 13, 2020
Paul, Thank you for your review. We apologize that you were unsatisfied with your experience with this sprayer. Our goal is to give each customer the best experience possible with our products. Please consider calling our knowledgeable customer experience team at 800-253-4642 to improve your experience, troubleshoot with you, and to answer any questions you may have. We look forward to hearing from you! RLEchoHDX
  • DIY
  • Verified Purchase
1 found this review helpful
I bought this backpack sprayer today. After assembling it, I learned that the pump handle had on...
I bought this backpack sprayer today. After assembling it, I learned that the pump handle had only two positions. The first position is at a vertical position with the backpack and is for transport. The second position is a horizontal position, but the problem is that the handle is so far down, it is difficult to actually pump the sprayer. This was an easy fix. I drilled two opposing holes on the handle, which positions the handle at a 45 degree position, which makes it much more easier to pump.
    • Recommended
    3 found this review helpful
    Poor pump design
    This is a decently built sprayer but after the first use I found the pump stroke to be extremely short. After further investigation I found the diaphragm arm hits the plastic shroud that covers the diaphram. This requires lots of short strokes to pump the unit excessively to keep pressure. Of course this resulted in a worn out arm by the time I finished the first tank of spray application. After looking for the receipt which was gone months ago I opted to take my Dremel tool and cut away the plastic that was impeding the pump arm which made the unit more user friendly. After reading some of the posts here about "clicking" and "popping" during use I can only assume this is a design flaw rather than a one time incident. I have since relegated this unit to weed killer as I don't apply much of that and have purchased another brand for my heavier spraying jobs.
    • Pro
    18 found this review helpful
    Perfect except for the instructions!
    I'm throwing all my other sprayers out! Sits comfortably on your back and requires no bending. Just what my back needed. The shoulder straps are padded with a chest strap so it's comfortable to wear. It holds 4 gallons but I would not want to carry that much weight around which is not a problem cause it is easy to refill. It comes with additional pieces to change the spray but would have to guess how to change them. The factory setting spray is totally fine though so not sure I would ever have to change it. It was a nice even spray without any leaking. It arrived almost completely assembled which was great since the instructions were completely useless which is the only reason I gave it a four rating. The sprayer is also easy to clean
    • DIY
    • Recommended
    5 found this review helpful
    Great Sprayer
    This is going to be the perfect garden sprayer for my 1,600 square foot garden. I spray diluted neem oil as a pest deterrent, and this is going to make the job so much easier. My old handheld garden sprayer's capacity was 1.25 gallons, and I would usually have to make three trips with it to cover all the rows. I took this for a test run with plain water, and I'm pretty impressed with how easy it was to use, even though the instructions were very minimal. I filled it all the way up, and I'm glad its capacity is not more than 4 gallons, which comes out to about 33 lbs. The straps have a little bit of padding, but not a ton. Fortunately, the sprayer sits very comfortably without putting a lot of weight directly downward on the straps. When the waist strap is fastened, it puts a good portion of the weight on my hips and the shoulder straps mostly keep it balanced. The pump mechanism was a little awkward to work, although it doesn't take very much effort. It can be positioned at either the vertical or horizontal position. However, it's very difficult to reach up when the pump arm is at the vertical. When it's horizontal, pumping it downward nearly puts the lever arm out of my reach. It would have been nice if I could adjust it to be at 45° instead. The sprayer handle is comfortable to hold. The trigger is easy to squeeze, and can even be locked on for a continuous spray. The wand is bent at the end so I can hold my wrist at a natural position while spraying. The only real complaint that I have is that the wand holder on the side of the sprayer doesn't work well at all (see picture). It's extremely difficult to snap it in place, and it pops right back out within five seconds of securing it. The wand holder on the top of the lid works well, but gives the sprayer a much bigger footprint for storage. I'm a little confused as to the purpose of the three extra plastic pieces included with the sprayer. They look like they're meant to be spray tips for a nozzle assembly, but I don't see how they would fit with the included nozzle. Maybe they're replacement parts for some internals of the sprayer? Might have been nice if Echo included a description in the instructions.
    • DIY
    • Recommended
    4 found this review helpful
    Great product but instructions could be improved
    We decided to try this diaphragm backpack sprayer as an alternative to our smaller 2.5 gallon pump sprayer. We use the sprayer for everything from spraying insecticide around the perimeter of the house to weed killer to deck sealer however it is difficult to fully clean out the deck sealer and the old piston pump sprayer’s performance has suffered as a result. Reading up online, diaphragm pumps seem to handle the soluble powders a little better than piston pumps, particularly if the powders don’t fully dissolve. Since we were spraying a soluble borax-based termite treatment and also use water seal on our deck every couple of years, we decided to switch to the diaphragm sprayer. The pump requires hardly any assembly out of the box, about 5 minutes max. The pump handle can be mounted on the left or the right side to suit left or right handed use and switching it over to the opposite side takes a few seconds as it’s held on with a single spring clip. It takes a few primes of the handle to get the pump up to pressure and is easier to keep at pressure than our smaller piston pump sprayer as its strapped to your back and therefore very stable when you’re using the priming handle. The sprayer comes with a variable nozzle that can be finger adjusted between a fine fan spray and a single jet spray. There are also three separate nozzles which are useful if you are spraying something like deck sealer, stain or water proofer as they are easier to dismantle and clean than the variable adjuster nozzle. The blue nozzle creates a ‘fan’ spray, the domed nozzle creates a fine jet spray while the dual nozzle creates two opposing jets angled at about 45 degrees. The fixed nozzles and their spray patterns can be seen in the photos attached to this review. Unfortunately the instructions don’t explain how to use the extra nozzles. Through trial and error I was able to figure out that the black adjustable spray tip has to be dismantled in order to re-use the black plastic nut that screws it onto the end of the spray wand. You’ll need to use a small screwdriver to help tease the rubber washer out of the nut and then some pressure to push the spray tip out of the nut (after you have removed the fan adjustment tip from the spray tip) as there’s a small rubber ‘o’ ring on the tip that interferes with the nut. Just look at the pictures attached to this review and you’ll see what to do – something like this would be helpful in the instructions however. Even better would be an extra plastic nut so you can avoid dismantling the variable spray head altogether. The other item that was missing was a pressure relief valve for de-pressurizing once the job was done, however the tank lid screwed off easily and there was no back splash when the lid was loosened and the pressure released. One thing I really liked about the sprayer is the size of the opening at the top of the spray tank. It measures about 5 ½” round and this makes it easy to get your hands in to reach the bottom of the tank with a sponge if there is some residue from deck stain or sealer left over after rinsing out the tank. The top of the tank also has a removable strainer although it is quite a coarse strainer so it will not stop smaller particles from getting into the tank. I also liked the fact that the spray handle has a security clip, so if the sprayer is loaded with something harmful or messy, you can lock the trigger to keep it safe from children. The spray wand can also be clipped onto the spray tank lid so it can be securely stored when not in use. We mixed up a powdered borax-based termite treatment to spray 8’ high x 40’ long interior stud wall and attached sheathing of our garage as part of a garage re-model and the backpack sprayer helped us get the job done in about 10 minutes. This job would have been a pain with our smaller pump sprayer as I would have been constantly stopping to re-prime the pump and also holding the pump tank in one hand in order to reach the tops of the wall.
    • DIY
    • Recommended
    17 found this review helpful
    Easy to Use Sprayer
    Having a sprayer as a backpack is the only way to go. All my other sprayers were hand-held units. Not only were they heavy to carry, but you had to stop to pump-up pressure all of the time. With the pump handle right along your side, you can conveniently pump as you go. I don't ever see going back to my old sprayer routine again. The gallon measurements on the side were not easy to see. To help this situation, I used a permanent marker to highlight the gallon and half gallon measurements.
    • Pro
    • Recommended
    4 found this review helpful
    The good quality, durable sprayer, in new user friendly technology.
    The Echo Diaphragm technology sprayer is better than the conventional piston pump, since I do not have to unload it from my back to pump air. I can go all the way until the tank is empty; just keep on pumping air occasionally, while it is still on my back, when the pressure is down. It is a heavy duty sprayer, well made , with all durable materials, and easy to carry on the back. The Diaphragm-Pump Backpack Sprayer is designed for use with powders, liquids and water-soluble solutions., but not flammables, caustics or bleach. (do diligence) The pumping handle liver can be used for left- and right-handed application. I have tested the sprayer and I am very happy with its performance. The spray is powerful, no leaks anywhere and very easy to pump and pressurize when on back. Please see my video to see the spray in action and also the diaphragm technology at the bottom of the sprayer. Thanks Echo, for the good quality and durable sprayer in a new user friendly technology.
    • DIY
    • Recommended
    22 found this review helpful
    Easy to use
    I have 5 acres of land so this 4 gallon sprayer allows me to spray most of the weeds growing on my property without filling up a second time. It is remarkably comfortable but at 60 years old my shoulders do get a little tired even with the heavy duty pads. I set it on my work bench and back into it to attach the harness to my body. This sprayer is well made and carries a lifetime warranty. Keep the o-rings greased and it will function flawlessly. You can use it for liquids and powders and it won't clog. I like the large opening to pour the water in so it keeps me from getting the whole tank wet. It has a pressure chamber so you don't have to be pumping the whole time you are using it.
    • DIY
    • Recommended
    20 found this review helpful
    Showing 1-10 of 483 reviews