The best knapsack sprayers, compared.
Top pick: SEESII battery knapsack Best value: Faithfull 16 L knapsack sprayer – Best value at about £37.69: score 71, 4.3 from 1,149 reviews, a service kit and a stated five-year warranty. Updated October 2026.
A knapsack sprayer is a backpack tank with straps, a hose, a lance and a nozzle. You pump it with a hand lever, or a battery holds the pressure. You buy one when a 5 litre shoulder bottle means constant refilling on a drive, a path or a lawn. Water is about 1 kg per litre, so a full 20 litre tank is a heavy walk. Judge the litres you can carry, the harness, and whether a battery listing names the charger. A stated 100–150 is a maximum, not a coarse weed setting. Amateur weed killers at home do not need a certificate if you follow the label. Litres, pump and harness are in the [knapsack sprayer buying guide](/hub/garden-tools/knapsack-sprayer/sub/knapsack-sprayer-buying-guide). Handheld compression sprayers of about 1.5–8 litres are for spots. The & 5 was a handheld pressure sprayer one strap, and it is not.
A knapsack sprayer is a backpack tank with straps, a hose, a lance and a nozzle. You pump it with a hand lever, or a battery holds the pressure.
38 products checked · 64 hrs invested · +24,100 readers
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Personal buying guide
Question 1 of 2
How will you pressurise it?
The SEESII battery knapsack, model PWQFT01, is listed at £159.99, the highest price in this set, with 4.7 from 33 amazon.co.uk reviews. Thirty-two review texts are in the file and all are marked United Kingdom, which is a complete small sample rather than a deep one. Buyers describe less fatigue than a manual pump on decking and algae, a metal lance, and little battery drop after 40 minutes. The box list is the fullest battery kit here: two 2.0 Ah packs, a charger, a brass telescopic wand, seven nozzles, a screen filter and O-rings. The title says 18 litres and the specification says 5 gallons, without saying imperial or US gallons, so the tank size is not one number. One reviewer says the battery compartment has no seal and water gets in, and another calls the shell cheap. A review quotes £109.99, which is not this capture’s £159.99. The stars are not enough evidence to treat it as the top pick.
Pros
Cons
Best for: You want two packs and a brass wand in one box and you will confirm the tank size on the live page.
Less suitable: You want the top pick to rest on hundreds or thousands of reviews, or a single stated tank volume.
Specifications
Common questions
How big is the tank?
The title says 18 litres. The specification field says 5 gallons. The listing does not say whether that gallon is imperial or US.
What batteries are included?
Two 2.0 Ah batteries and one charger. The bullets say each battery lasts up to 1 hour and 48 minutes.
What warranty is stated?
The bullets say a 3-year manufacturer warranty and lifetime technical support. The hose is listed at 45.6 inches, about 116 cm.
The SideKing 16 litre battery knapsack, model YL8017-16L, is listed at £89.99 and starts spraying from a switch, which is what the first 50 United Kingdom reviews describe instead of a lever. Those texts sit under a 4.6 from 277 line on amazon.co.uk. One of them reports 25 litres of herbicide with the battery still full. The included line names the battery, a telescopic stainless wand, a fixed plastic wand, five nozzles, a measuring cup, padded straps, a waist belt and two O-rings. A charger is not on that line, so a wall charger is not confirmed from the components field. One reviewer called the metal lance poor, and another thought parts were missing until they turned up in the packaging. The bullets also claim Makita 18 V compatibility. This is a SideKing sprayer, not a Makita tool, and 100 PSI, also written as 7 bar, is the stated maximum, not a weed-killer setting.
Pros
Cons
Best for: You spray often enough that a lever hurts, and you want a 16 litre battery backpack with a waist belt and a thicker review sample than the 33-review SEESII.
Less suitable: You need a charger named on the included line, or you only treat a few weeds with a small bottle.
Specifications
Common questions
Does this SideKing include a battery?
Yes. The included-components line lists a battery. A charger is not named on that line. The listing also says the sprayer can use Makita 18 V batteries. This is a SideKing sprayer, not a Makita tool.
How much pressure does the listing state?
The specification says 100 PSI. The bullets also write 0–100 PSI, or 7 bar, adjusted on a knob. That is the stated maximum, not a weed-killer setting.
Is there a waist belt?
Yes. The included parts list padded shoulder straps and a waist support belt.
The SYLSTAR 20 litre battery knapsack is listed at £103.99, and the title says a 2.6 Ah battery plus compatibility with DeWalt and Milwaukee 18 V packs. The amazon.co.uk line is 4.4 from 132, with 33 of the first 50 texts marked United Kingdom. One user put 64 litres through it with the battery still on three bars, and reviewers call it easier than a hand-pump backpack. The components field names a battery charger, and nozzles are described as stored in the battery compartment. Empty weight is 4.85 kg before about 20 kg of water, so a full tank is a heavy carry even with the pump switched on. One unit stopped after a month, and another shows a full charge with no lights and a pump that does not run. The filler cap is not captive. The DeWalt and Milwaukee lines are compatibility claims on a SYLSTAR listing, not those brands’ sprayers, and 120 PSI is the stated maximum.
Pros
Cons
Best for: You already own DeWalt or Milwaukee 18 V packs and you can carry a 20 litre fill.
Less suitable: You want a lighter 12 or 16 litre tank, or a battery story with fewer dead-pack reviews.
Specifications
Common questions
Will it take a DeWalt or Milwaukee battery?
The title and bullets say it is compatible with DeWalt 18 V and Milwaukee 18 V batteries. The title also says a 2.6 Ah battery. The components field names a battery charger. Those lines are a SYLSTAR claim, not a DeWalt or Milwaukee sprayer.
What wands are described?
A telescopic stainless wand up to 39.3 inches and a fibreglass wand. 39.3 inches is about 100 cm.
What tank size is stated?
20 litres. Empty weight on the listing is 4.85 kg. A full tank is about 20 kg of water before that empty weight.
The Faithfull FAISPRAY16 is a 16 litre hand-pumped knapsack listed at £37.69, with 4.3 from 1,149 amazon.co.uk reviews and the first 50 texts marked United Kingdom. Reviewers say it holds up at about 80 percent full, and several put the tank on from a patio table because of the weight. The title includes a service kit and three adjustable nozzles, and the listing states a five-year manufacturer warranty. Pressure falls unless you keep pumping, which those reviews treat as the working method rather than a surprise fault. Instructions are called poor or missing, and the shoulder straps could be more comfortable. The specification field says a 1.5 metre hose while the bullets say a 140 cm hose and a 90 cm lance. It is the best value here if you will pump a lever and you want a long review trail with a service kit in the box.
Pros
Cons
Best for: A first 16 litre lever knapsack when you want spare parts in the box and a large amazon.co.uk review sample.
Less suitable: You want a battery pump, or a waist belt named on the listing.
Specifications
Common questions
Does it include a service kit?
Yes. The title and the supply line include a service kit and three adjustable nozzles.
What warranty is stated?
The listing says a five-year manufacturer warranty.
How long is the hose?
The specification field says 1.5 metres. The bullets say a 140 cm hose and a 90 cm lance.
The SYLSTAR 12 litre battery knapsack, model ST12L-7.4VDXD-BU, is listed at £41.99 with 4.3 from 1,032 amazon.co.uk reviews, and the first 50 texts are marked United Kingdom. Buyers who came from a 20 litre manual sprayer say it removes the pumping, and they use the three settings and the nozzle patterns on a useful area from the smaller tank. Empty weight is 2.16 kg, the lightest stated weight in this set, and the hose is only 60 cm. The bullets describe dual 2000 mAh packs and a 7.4 V handle, while the included-components field says only a nozzle and a garden sprayer, so the box is not settled from one line. One unit charged once and then would not charge, and a promised replacement was not received. Nozzles are called brittle, and one broke while the owner was stopping a leak. It is the low-price battery in this set if you accept a 12 litre tank and you check that both packs are actually in the parcel.
Pros
Cons
Best for: You want the cheapest battery backpack in this set and a 12 litre tank is enough for the job.
Less suitable: You need a 16 or 20 litre tank, a long hose, or a box list that names the batteries.
Specifications
Common questions
What battery does the listing describe?
The bullets describe dual 2000 mAh batteries and a 7.4 V handle with three settings. The included-components field only says nozzle and garden sprayer.
What is the stated maximum pressure?
The specification field says 150 PSI. That is a stated maximum, not a weed-killer setting.
How long is the hose?
The listing says 60 centimetres.
The SideKing 16 litre battery knapsack with a 4000 mAh pack is listed at £99.99, and the included line names a charger, five nozzles, an adjustable wand, straps and two O-rings. The amazon.co.uk line is 4.3 from 171, and the first 50 texts are marked United Kingdom. One user did four covers with about half the charge left, and another kept going through several 16 litre woodland fills. A buyer who had blistered hands from a hand pump on a large drive is the practical case these reviews describe. The specification says 120 PSI, and the bullets also claim a 5 metre stream, which is headroom rather than a weed setting. After a fall, one review says the straps burst and the large nozzle broke, and spare-parts contact is called unclear. It suits a 16 litre battery job when you want the charger named in the box, and it is a weaker match if you need the larger review sample on the other SideKing.
Pros
Cons
Best for: A large drive where a hand pump has already blistered your hands, and you want the charger written into the box list.
Less suitable: You want the cheaper SideKing with more reviews, or you need a manual sprayer with no battery to charge.
Specifications
Common questions
Is a charger included?
Yes. The included-components line lists a battery charger, and the bullets specify a 4000 mAh battery.
Which wands are described?
The bullets describe a 41 inch stainless telescopic wand and a fibreglass wand. The components line says an adjustable-length spray wand. 41 inches is about 104 cm.
What pressure is stated?
The specification says 120 PSI. The bullets also claim a 5 metre stream. That is headroom, not a weed setting.
Oregon’s 16 litre backpack sprayer, model 646608, is listed at £50.80 with 4.2 from 3,345 amazon.co.uk reviews, the largest count in this set. The first 50 texts are marked United Kingdom, and dates in that sample start in 2016, so the count may include older listing history. Reviewers describe a lever pump even though the specification block does not state a power source. Once the pump is tight they praise the fan spray, the spare seal kit and the four nozzles, named as flat fan and adjustable cone. The pump arrived loose for some buyers, with mix running down the back, and one plastic pump handle cracked within a year. Straps are said to lack padding on a full tank, and one older review discusses a 20 litre fill that does not match this 16 litre title. Choose it when you want the deepest review file and a seal kit, and tighten every fitting with water before any chemical.
Pros
Cons
Best for: You want the longest amazon.co.uk review trail in this set and a spare seal kit, and you will test the pump with water first.
Less suitable: You need a battery pump, or a power source printed on the specification line before you order.
Specifications
Common questions
Is the Oregon battery powered?
The specification block does not state a power source. The bullets describe a pressurised chamber. Reviewers describe a lever pump.
What nozzles are included?
Four choices, named as flat fan and adjustable cone, plus a spare seal kit.
What capacity is on the title?
16 litres. One older review in the file discusses a 20 litre fill. That does not match this title.
The Mobiclinic Fumibug is a 16 litre hand pump listed at £42.95, with 4.0 from 569 amazon.co.uk reviews. Only 7 of the first 50 texts are marked United Kingdom, so the themes below are from that mixed sample of 50, not a UK-only cut. The bullets say the sprayer converts into a backpack, the style field says Backpack, and the specification says 3 bar while the bullets say 2–3 bar. One UK reviewer calls it light and leak-free, and others praise the hose ends for a large garden. The same sample keeps returning to straps: they need padding, one does not lock, they are not permanently fixed, and a plastic strap piece was missing. When the straps fail, reviews say the tank can drop onto the calf. The title area says a lightweight 2 kg and the specification says 3.23 kg. At this price you are paying more than the Faithfull for a conversion backpack whose straps are the complaint.
Pros
Cons
Best for: You want a 16 litre hand pump with a printed 3 bar line and you will inspect the strap fixings before you fill it.
Less suitable: You need straps that reviews describe as staying locked, or a UK-only review sample.
Specifications
Common questions
Does it work as a backpack?
The bullets say the pressure sprayer converts into a backpack. The style field says Backpack. Reviews say the straps are not permanently fixed.
What pressure is stated?
The specification says 3 bar. The bullets say 2–3 bar. That is the one manual listing here with a printed pressure near the foliage range TreeMarker describes.
Why do the weights disagree?
The title area says lightweight 2 kg. The specification says 3.23 kg. Both figures are on the listing.
The Spear & Jackson 15LPAPS is a 15 litre hand-pumped backpack listed at £26.45, with 4.0 from 462 amazon.co.uk reviews and the first 50 texts marked United Kingdom. The bullets say you can operate it from the left or the right, and the box includes an adjustable nozzle plus three extra nozzles. Reviewers say it covers large areas, and some report no leaks compared with other brands they have owned. Shoulder-strap clips are called weak or slippery, and one user tied the straps on. The pump handle pushes onto the shaft and feels loose, and one buyer returned the unit for design flaws around that handle. The material field says Metal, which does not match a plastic garden tank and should be read as an unclear line. Liquids other than water are limited on the listing to pH 5 to 9. At 4.2 kg empty it is a mid-size manual tank, and the clip complaints matter once the 15 litres are full.
Pros
Cons
Best for: You want a 15 litre lever tank you can pump from either side, and you will check the strap clips before a full fill.
Less suitable: You need a waist belt, a stated pressure, or strap clips that reviews describe as staying put.
Specifications
Common questions
Can you pump it left-handed?
The bullets say it can be operated from the left or the right.
What liquids does the listing limit?
Where the liquid is not water, the bullets say pH 5 to 9.
How many nozzles are included?
An adjustable nozzle plus three additional nozzles.
The Optimal Products 20 litre pump, model 1254, is listed at £22.95 with 3.9 from 162 amazon.co.uk reviews, and the first 50 texts are marked United Kingdom. The bullets say a handy shoulder strap, an adjustable nozzle and a trigger lock, and the item-type field says Spray Gun, while UK reviews describe a backpack strap and a drum, so it is a borderline backpack rather than a harness you can specify from the title. Some buyers say it is acceptable at the price if every fitting is tight. Others say the strap clip failed within minutes, the drum rotated and the mix spilled, and one tank split along the bottom on a first fill. Several say it will not hold pressure because air leaks at the lid, and the instructions and photos did not match the unit. At 2.7 kg empty and 20 litres full, the water is still about 20 kg. Treat it as the cheap end of the table, not as a proven knapsack harness.
Pros
Cons
Best for: You are comparing the cheapest 20 litre pump in this file and you will pressure-test it with water only.
Less suitable: You need a backpack harness the title describes, or a tank reviews do not describe as splitting.
Specifications
Common questions
Is this described as a backpack?
The bullets say a handy shoulder strap. The item type field says Spray Gun. UK reviews describe a backpack strap and a drum, so it is kept as a borderline knapsack.
Does it have a trigger lock?
Yes. The bullets say a fully adjustable nozzle and a trigger lock.
What is the empty weight?
The listing says 2.7 kg, with a 20 litre tank and a 1.5 metre hose.
The ASC 20 litre manual knapsack, model ASC_20LTSpray, is listed at £29.20 with 3.6 from 420 amazon.co.uk reviews, and the first 50 texts are marked United Kingdom. It is a hand lever: one hand sprays while the other pumps, and the empty weight is 3.2 kg before a 20 litre fill. Reviewers who get it assembled say it works on lawn weeds, and one owner was still using a unit bought in June 2018. Spare washers were needed and were in the kit, along with spare spray heads, seals and pins. The same reviews say it does not hold pressure, the instructions have no diagrams or are missing, and the pump arm is flimsy, bent or nearly snapped. Strap parts are missing or fitted backwards. A low price does not remove about 20 kg of water. It is a cheap 20 litre lever only if you will rebuild the pump and the harness before you trust a full tank.
Pros
Cons
Best for: You want a cheap 20 litre lever and you will fit the spare seals before the first chemical fill.
Less suitable: You want a sprayer that reviews say holds pressure, or a tank you can carry full without a 20 kg load.
Specifications
Common questions
Is this a battery sprayer?
No. The listing describes a hand lever: one hand sprays while the other pumps.
What spare parts are listed?
Spare spray heads, seals and pins.
How heavy is the empty tank?
The listing says 3.2 kg. The tank volume is 20 litres, so a full fill is about 20 kg of water before that empty weight.
Scores compare the eleven amazon.co.uk listings kept in this category. Prices, stars and review counts are the figures saved on 19 October 2026. There is no laboratory spray test and no NSTS certificate. The scores do not name the best knapsack sprayer in Britain. Each working score uses four caps: 35 for stars, 25 for review volume, 20 for the kit, and 15 for review themes. Those caps sum to 95. The weights below are those shares scaled so they sum to 100. Listing conflicts are deductions inside the score, not a fifth award.
Stars
37%Amazon stars as (rating minus 3.0) times 20, rounded, and capped at 35 in the working score. A 4.7 becomes 34. A 3.6 becomes 12. The page weight is 37, the same share scaled so the four weights sum to 100.
Review volume
26%Review-count bands, capped at 25 in the working score: 2,000 or more scores 25, 1,000 or more scores 22, 500 or more scores 18, 300 or more scores 15, 200 or more scores 12, 100 or more scores 9, 50 or more scores 5, and under 50 scores 2. A 4.7 from 33 does not outrank 4.2 from 3,345. The page weight is 26.
Kit
21%Kit points, capped at 20 in the working score: a named battery and charger, a waist belt or padded straps, numbered nozzles, spare seals or O-rings, and one tank volume that does not fight another line on the same page. The page weight is 21.
Review themes
16%Review themes, capped at 15 in the working score, from pumping removed, pressure loss, strap clips, dead packs and splits. A lever that needs pumping is a smaller deduction than a tank that will not hold pressure. The page weight is 16.
Choose the litres you can carry, then lever or battery, then the harness. A 5 litre bottle is not a knapsack. Prices below are amazon.co.uk shelf prices on 19 October 2026. Lever against battery is set out in [battery or manual knapsack sprayers](/hub/garden-tools/knapsack-sprayer/sub/knapsack-sprayer-battery-vs-manual).
A knapsack sprayer is a backpack tank with straps, a hose, a lance and a nozzle, pumped by a hand lever or a battery. You buy one when a 5 litre shoulder bottle means constant refilling on a drive, path or lawn. Handheld compression sprayers of about 1.5–8 litres are for spots. The Spear & Jackson 5LPAPS was a handheld pressure sprayer with one strap, and it is not in this set. Manual knapsacks kept here are 15, 16 or 20 litres with a lever.
A handheld compression sprayer of about 1.5–8 litres is for spots. It is not a backpack tank. The Spear & Jackson 5LPAPS was that kind of bottle and is not in this set.
Water is about 1 kg per litre. A 20 litre fill is about 20 kg before the empty sprayer. TreeMarker’s rule of thumb puts a loaded 15 litre knapsack at roughly 18–20 kg. Carry what you can walk with.
100 PSI, 120 PSI and 150 PSI on these battery listings are maximum headroom. TreeMarker puts forestry weeds near 1 bar and foliage up to 3 bar. Follow the product label, and do not leave mix to dry in the nozzle.
The first check is the fill you can walk with, not the largest number on the tank. Water is about 1 kg per litre. Empty weights in this set run from 2.16 kg to 4.99 kg. A 15 litre load is already in the high teens of kilograms once the tank is included. A 20 litre fill adds about 20 kg of water on top of the sprayer. The SideKing 16 litre at about £89.99 lists a waist belt and padded straps, at 4.1 kg empty.
A lever is cheaper and has no pack to fail. Pressure falls unless you pump. Faithfull reviews treat that pumping as the working method. A battery holds pressure without it. The Weed Guy describes that low, steady pressure for driveway work. Battery prices in this set run from about £41.99 to £159.99. Do not read 100 PSI, 120 PSI or 150 PSI as the weed setting. Those are stated maximums. TreeMarker puts forestry weeds near 1 bar and foliage up to 3 bar.
Three typical situations, each with a recommendation from this comparison.
You use an amateur weed killer as the label allows, and a 5 litre bottle means constant refilling. The Faithfull is a 16 litre lever with a service kit, a stated five-year warranty, and 4.3 from 1,149 reviews. Pressure falls unless you pump.
You spray often enough that a hand pump hurts, and you want a 16 litre battery backpack with a waist belt. The included line names the battery. A charger is not on that line. The stated 100 PSI is a maximum, not a weed setting.
Spraying is your job, so PA1 plus PA6 and a recorded inspection apply. These listings are not NSTS-tested. Do not treat the cheapest 20 litre pump as a trade knapsack. In this set the Oregon has the largest review count, and you still test it with water first.
In this set the top pick is the SideKing 16 litre battery knapsack, model YL8017-16L, at 72 and about £89.99. It has a waist belt, an included battery, 4.6 from 277 reviews, and few leak comments in the first 50 United Kingdom texts. The charger is not on the included line, which is already in the score. Best value is the Faithfull FAISPRAY16 at 71 and about £37.69. The score is one point behind, with 4.3 from 1,149 reviews, a service kit and a stated five-year warranty. It is a lever, so pressure falls unless you pump. The SEESII at 4.7 from 33 stays off both awards: the volume term is 2, and the title says 18 litres while the specification says 5 gallons.
Faithfull 16 L knapsack sprayer
Best value at about £37.69: score 71, 4.3 from 1,149 reviews, a service kit and a stated five-year warranty.
Editorial
Peter F. is the editor for DIY & tools at productscompared.co.uk. Comparisons in this category are checked against amazon.co.uk listings, review evidence and public UK sources.
Guides on what to look for, how to use a product, and common mistakes.
Public UK sources used for this comparison. Listing prices, stars and review counts are from amazon.co.uk on 19 October 2026.
This page contains affiliate links to amazon.co.uk. If you buy through them, we may earn a commission at no extra cost to you. Prices, stars and review counts are the UK listing lines. We did not run a lab test.
