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Bench Test · 11 min read
Self-washing, self-emptying, self-refilling. We measured whether the RockDock's convenience survives six months of real use.
By Robot AutoTrader Bench Team · 5 June 2026 · Unit bought at retail
The most complete floor-care robot we've bench-tested. Used units with dock under £700 are the value sweet spot of the entire category.
Placeholder artwork — test photography appears here in production.
Six months, 178 completed runs, and precisely one moment of manual intervention — a sock, and arguably the sock's fault. The S8 Pro Ultra's pitch is that the RockDock Ultra does everything: empties the bin, washes the mop, refills the tank, dries the pads. Our logs say the pitch holds. We touched the robot itself so rarely that the dust on its lid became a running bench joke, which is an odd look for a vacuum.
At £1,499 it was a hard sell new. It is not a hard sell now. Clean used examples with the full dock are trading at £620–£690 on our marketplace, and at that money nothing else pairs this carpet performance with genuinely unattended mopping. The dock is the product; the robot is the accessory. Buy accordingly — a used unit without the dock is half a machine at two-thirds the price, and our 9.1 assumes the dock comes with it.
Our standard domestic protocol, mop edition: a 94 m² two-floor home, mixed oak and medium-pile carpet, one moulting Labrador on loan from the j7+ test, daily scheduled vacuum runs and alternate-day mopping for six months. Debris scores use our weighed-pickup method — 20 g measured mix of rice, oats and dog hair per zone. Mop scores use our dried-on test: 5 ml of coffee left on oak for 24 hours, passes counted until it's gone.
| Hard-floor pickup (weighed) | 97% new | 96% at 6 months |
|---|---|---|
| Carpet pickup (weighed) | 88% new | 86% at 6 months |
| Dried coffee removed, 2 passes | 93% new | 84% at 6 months (fresh pads: 91%) |
| Battery runtime (measured, max suction) | 168 min new | 159 min at 6 months |
| Dock mop-wash cycle (measured) | 2 min 40 s new | 2 min 55 s at 6 months |
| Obstacle avoidance (30-object course) | 24/30 new | 24/30 at 6 months |
| Failed / abandoned runs | — | 3 of 178 (98.3% completion) |
The RockDock is why you buy this machine, so we costed it properly. Six months of consumables: five dust bags at £3.20, one set of mop pads at £14, one filter at £9, and 40 litres of tap water the dock quietly drank from its 2.5 L clean tank. Roborock's own detergent is £12 a bottle and we measured no cleaning difference against plain water on sealed floors, so we stopped buying it in week three. Call it £110 a year all-in for a pet home — a fiver a year more than the j7+, for a machine that also mops.
The hidden cost is your time at the dock, not your wallet. The dirty-water tank needs emptying roughly weekly (we logged a 9-day average before the app nagged) and the wash tray wants a rinse every fortnight. Skip the tray and it tells you within a month, olfactorily. Total measured human labour across six months: 84 minutes. Our upright vacuum demands that in a fortnight.
Battery first, because that's what used buyers pay for: after 178 cycles our pack reports 95% health, and measured runtime fell from 168 to 159 minutes — about 1% a month, tracking slightly better than the j7+'s curve because the dock tops up little and often rather than deep-cycling. Extrapolated, a two-year daily-use example should still hold ~80%, and on a 94 m² home it finishes with margin to spare even at max suction.
The real wear item is the mop system. Pads are done at three months, not the six Roborock implies — our coffee score fell nine points on worn pads and recovered eight on fresh ones, so treat pads as a consumable, not a keepsake. The other thing to watch is the dock's wash tray: in our hard-water postcode it grew visible limescale by month four, and the wash cycle slowed 15 seconds as the scraper worked around it. Ten minutes with descaler fixed it. A neglected one is the single best tell of a carelessly kept machine.
How we fund this: Bench Test units are bought at retail. If you buy a new robot through outbound retailer links we may earn an affiliate commission; it never affects scores, and used listings on Robot AutoTrader carry no commission in this phase.