Best Window Vacuum 2026: 10 Ranked on Tank Size, Not Runtime

One hundred and fifty millilitres is half as much again as the next largest tank on this page, and it belongs to the cheapest machine in the comparison. That is not a coincidence worth celebrating so much as a demonstration of how little the category thinks about the spec: Tower has fitted a proper reservoir and priced the machine at £22.99, while the £62.99 Kärcher at number three does not print a tank figure anywhere in its bullets.

On a British winter morning that difference is the whole experience. Condensation on a double-glazed unit yields roughly 20 to 30ml per pane in a bad week, so 150ml gets you through five or six windows before a trip to the sink, where 60ml gets you two. Thirty minutes of runtime on a 20W motor is more than enough to empty that tank several times over.

The 4.2 average across 1,592 ratings is the lowest of the top four here, and it is the honest counterweight — this is a value brand, not a precision instrument, and the build reflects the price. Note too that Tower sells this exact model under three ASINs with colour suffixes, all showing the same 1,592 ratings and the same 4.2, at £22.66, £22.99 and £24.98. Same machine, same review pool, three prices. Check all three before you click; we have linked the middle one.

Kärcher invented this category and the WV 1 is where its range starts. The specification is honest and complete in a way the rest of the Kärcher line here is not: a 100ml dirty water tank, 20 minutes of battery, and a weight of just 0.5kg. It is the only Kärcher on this page that puts a tank figure in its bullets at all.

Half a kilogram is the number people underestimate. A window vac is used at arm's length, above shoulder height, repeatedly — and the difference between 500g and the 924g Bosch is felt in your forearm by the fourth window. For anyone doing a whole house of condensation on a January morning, light beats powerful.

The 20 minute runtime is the shortest in this comparison and it looks like a weakness until you do the arithmetic. Twenty minutes is plenty to fill a 100ml tank two or three times over, which is more windows than most people clean in a session. Compare it with the Beldray at number ten, which sells 30 minutes and holds 60ml: the Beldray runs longer and stops sooner. Kärcher has sized the battery to the tank rather than to the marketing, and at £29.99 with 2,696 ratings at 4.4 it is the sensible default.

Ten thousand and fifty-one ratings at 4.5 stars is four times the evidence of anything else in this comparison, and it is the reason this machine sits third despite what follows. When ten thousand British households have bought the same window vac and settled on 4.5, the product works.

The package is the most complete here. Two suction nozzles cover both large panes and narrow reveals, there is a spray bottle with a microfibre cloth and 20ml of window cleaner concentrate so you can start the moment it arrives, and the LED battery display tells you where you stand rather than leaving you to guess. Thirty-five minutes of runtime is joint longest among the branded machines.

What Kärcher does not do on this listing is state the tank capacity, in any bullet, anywhere. That is a strange omission from the brand that publishes 100ml on its own entry-level WV 1, and it is the reason a £22.99 Tower outranks a £62.99 Kärcher in this article. If you are buying for a house with serious condensation, the number you need is the one this listing leaves out. Buy it for the evidence, the two nozzles and the kit; do not assume the tank scales with the price, because on this page it does the opposite.

This listing does what almost none of the cheap ones manage: it tells you everything. One hundred millilitre tank, 28cm rubber-lip nozzle, 35 minute runtime, and the battery specified precisely as 3.7V 2200mAh lithium-ion. For £24.99 from a brand nobody has heard of, that is a page written by somebody who understood the product.

The 28cm nozzle is the practical highlight. Blade width decides how many passes a pane takes, and 28cm is the full-size head that Kärcher fits to its more expensive machines. On a standard double-glazed unit that is two strokes rather than four, which over a whole house is the difference between a job and a chore.

The catch is evidence. One hundred and forty-three ratings at 4.4 is the second thinnest sample in this comparison, and with a new brand there is no history to fall back on — no way to know whether the seal lasts a season or three. It is also the machine that reveals the battery finding: it declares the same 2200mAh cell as two other units on this page and claims 35 minutes, where they claim 40 and 45 from identical hardware. DMD's is the most conservative of the three, which by the logic of this whole article is a point in its favour.

Bosch has done something quietly sensible and quietly unhelpful at the same time. Instead of quoting minutes, the GlassVAC is rated for approximately 35 windows per charge. That is genuinely the number a buyer wants — nobody cleans windows by the clock — and it is also impossible to compare with the nine other machines on this page, all of which quote minutes.

The blade is the reason to consider it. Bosch says the wiper technology comes from its automotive division, which is not marketing froth: Bosch is one of the largest windscreen wiper manufacturers in the world, and a wiper blade that clears a windscreen at 70mph will clear a bathroom mirror. Blade quality is what separates a streak-free finish from a smeared one, and this is the only listing here that can point at genuine pedigree.

Two caveats. At 924g it is nearly twice the weight of the Kärcher WV 1, which you feel on upstairs windows. And the specification table is careless in the way this whole category is careless — it lists Specific uses for product as Construction and ticks Contains liquid contents as Yes, neither of which describes a domestic window vac. At £52.99 with 1,944 ratings at 4.4, you are paying for the blade and the badge.

Two hundred and eighty millimetres. That is the number this listing gives you that the others in the Kärcher range do not, and it is worth having: nozzle width decides how many passes a pane takes, and 280mm is the full-size head rather than the narrow one. On a standard window that is two strokes instead of three or four.

The rest is the familiar Kärcher package at a sensible point in the range. Thirty-five minutes of battery, the LED status display, and the spray bottle with microfibre cloth and 20ml of concentrate so the machine is usable the moment it comes out of the box. At £44.99 with 1,004 ratings at 4.4 it sits between the entry WV 1 and the heavily reviewed WV 2 Plus N.

The honest question is what the £15 over the WV 1 buys. You get 15 more minutes of runtime, a wider published nozzle and the cleaning kit; you lose the published tank capacity, because like the WV 2 Plus N this listing never states it. Given that the tank is the limiting factor rather than the battery, that is a strange trade to be offered. If the wider blade matters to you — large windows, patio doors, a conservatory — take it. If you have ordinary domestic windows, the WV 1 at number two does the same job for £15 less.

Two nozzles for under £30 is a genuinely good offer. The 28cm head does full panes in two passes and the 17cm SlimLine gets into window reveals, down the side of a shower screen and along the glazing bars of a Victorian sash — the places where a wide blade simply cannot reach. Kärcher charges £62.99 for a machine with two heads; CubeTECH charges £29.95, and 2,073 buyers have rated it 4.3.

The battery is rechargeable lithium and the machine is a straightforward, unfussy design that does the job.

What it will not tell you is the one thing this article is about. The first bullet says the CTWV2 boasts a generous water tank capacity, enabling continuous cleaning without interruption — and then never gives a figure. Generous is not a specification. On a page where the tank runs from 60ml to 150ml, a manufacturer choosing an adjective over a number is choosing not to be compared. The same bullet block contains a typo, offering the SlimLine nozzle fro hard to reach areas, which tells you roughly how much the copy was checked.

This kit publishes something almost nobody else does: a suction figure, at 2 kPa. Suction is what lifts water off glass rather than smearing it, and having a number attached is more than the Kärcher, Bosch or Tower listings offer. Add both a 28cm and a 17cm nozzle and 4.5 stars from 329 ratings, and on paper it is a strong package for £39.99.

Then look at the battery. It declares 2200mAh and claims 40 minutes of runtime. The DMD Collective at number four declares 3.7V 2200mAh and claims 35 minutes. The EAVE at number nine declares 2200mAh and claims 45 minutes. Three machines, one commodity battery cell, three different answers spanning 29%. Motors in this class draw broadly the same current, so the honest conclusion is that at least two of those three numbers are estimates written by marketing rather than measured on a bench.

It also has a twin. A second listing carries an almost identical title, the same 329 ratings and the same 4.5 average, at £38.98 — a pound cheaper for the same product and the same review pool. We have linked this one because it was the one that surfaced first; check both, buy whichever is cheaper on the day, and take the 40 minute claim as a ceiling rather than a promise.

Forty-five minutes is the highest runtime figure on this page and it comes from a 2200mAh battery — the same capacity the DMD Collective rates at 35 minutes and the Window Vac Kit rates at 40. Three machines, one battery size, three answers. Since a window vac motor is a small fan and a pump drawing broadly similar current across this whole price bracket, that spread is not engineering; it is copywriting.

That is the reason this sits ninth rather than higher, because the rest of it is fine. Two kilopascals of suction is published, which several better-known brands do not manage, and 4.4 stars from 132 ratings is a reasonable start for a new listing at £29.99.

EAVE also has a near-twin on Amazon: a second listing with the same 45 minute title at £30.59 with 111 ratings against this one's 132. Not quite the shared-pool situation seen elsewhere on this page, but close enough that you should check both before buying. Given the choice at this price, the DMD Collective at number four costs £5 less, publishes a 100ml tank and a 28cm nozzle, and makes the most conservative battery claim of the three — which after a day of reading these listings is the quality we have learned to reward.