'What I wish I had known before buying a robot vacuum' by a shopping editor who's learnt the hard way

Robot vacuums are the kind of household innovation our grandmothers could only have dreamt of. Yet, they're now a mainstream household must-have rather than a futuristic flight of fancy, sold by all major appliance brands, including Dyson and Shark.

A robot vacuum is a wonderful thing to own. I wouldn't be without mine, but the list of things I wish I had known before buying one is long. So, if you're tempted to invest in one before Black Friday ends, I recommend first taking some time to understand what they can and cannot do. If you're picturing a world where you never have to pick up a vacuum cleaner again, I'm here to burst your bubble.

Robot vacuums can drastically reduce the time you spend cleaning your home - no more crawling under the table chasing crumbs after dinner - but they're not perfect. Some models empty their dustbins and can even mop the floor, which is impressive, but they can't handle everything.

They can't tackle stairs, for example, and - like most machines - they sometimes miss the things that humans would have spotted. So, to save you from splashing out on an expensive household gadget that turns out to be a disappointment, here's everything you need to know before you buy a robot vacuum.

What you need to know before buying a robot vacuum

Before we discuss the various factors to consider before buying a robot vacuum – such as your floor type, the size of your home, and any specific cleaning needs – it's worth taking the time to understand how they work.

You might not care much about vacuum cleaner mechanics but a basic grasp of how a robot vacuum works is essential to ensure you choose one that will live up to your expectations.

A robot vacuum uses sensors, motors, and algorithms to find its way around your home and clean your floors. Wheels allow it to move smoothly over different surfaces like carpet, hardwood floors and tiles, while brushes and a suction system pick up dirt and debris.

Some robot vacuum cleaners use mapping technology to ‘learn’ the layout of your space while the sensors enable it to avoid crashing into obstacles such as stairs, table legs and walls. Once the room is cleaned or the battery runs low, most robot vacuums return automatically to a charging dock.

1. They require supervision

The biggest thing I wish I had known before I got my robot vacuum was just how much help I would need to give it. Perhaps I was naive but this took me by surprise - and could become a bone of contention if you invested heavily in a robot vacuum without realising how much help it would need.

I envisaged setting my robot vacuum to work and forgetting all about it but in reality, I spend quite a lot of time supervising. They're designed to steer clear of obstacles, but they can easily get stuck. I've had to rescue mine from awkward entanglements with shoelaces, and rogue socks abandoned under my children's beds can be particularly problematic.

Mine frequently seems to lose its bearings under the sofa, ending up stuck, and don't get me started on the number of times I've had to dive into the path of the robot to save an expensive charging cable from an untimely end.

Our top 3 robot vacuum picks

If you're ready to go ahead, these three robot vacuums are our favourites, and they're all on offer for Black Friday:

2. They don't do stairs

Again, perhaps this was naivety on my part but I hadn't fully grasped, before buying a robot vacuum, that stairs would be off-limits.

It makes perfect sense - they have drop sensors to prevent them from getting too close to a step because they'd fall off, and design limitations mean they can't climb stairs. (Gravity probably plays a part too, as robot vacuums aren't exactly light.) So, if you live in a home with stairs, bear in mind that you'll almost certainly still need a traditional vacuum cleaner.

3. They require maintenance

The whole appeal of a robot vacuum is how much time it will save you, so it can be a little disappointing to discover just how much TLC they require to keep them running optimally.

With a robot, you have to clean the brushes regularly to maintain suction power and wipe down the sensors with a soft cloth to prevent problems with navigation. Then there's keeping the charging dock free of dirt and dust, cleaning the filter, and emptying the dustbin. Parts, like brushes and filters, will eventually wear out and need to be replaced, too.

No household gadget worth owning is entirely maintenance-free, of course, but it's important to note that a robot vacuum isn't a silver bullet for effortless cleaning; it's a machine that requires ongoing care and maintenance.

4. Pets can be a problem

I'm not talking about tackling pet hair - my robot vacuum is brilliant at picking up the worst of my puppy's fuzz when she's shedding her coat. Nope, the issue is that both my cat and dog despise the robot vacuum and regard it with the utmost suspicion.

To be fair, they're not huge fans of my cordless vacuum either so I wouldn't say this is a reason not to buy one. But I wish I had known, before buying a robot vacuum, that I would have to wait until the pets were sound asleep or out of the house before putting it to work.

5. Robot vacuums can be noisy

This one is definitely on me; who in their right mind would expect a vacuum cleaner to be quiet? It was a foolish expectation but it's important to disavow yourself of the notion that a robot will be a quieter alternative to a traditional vacuum. Unlikely. (But come on, it's cleaning the floor for you while you do something more fun; if it was quiet, too, we would be living in a perfect world.)

That said, I love the sound my robot vacuum makes. It's a bit like the feeling you get when someone powers up the best coffee machine to make you a fancy flat white; there's something strangely thrilling about the sound of your floors being cleaned while you find something more enjoyable to do.

Unlike the best dehumidifiers for bedrooms, it's not the end of the world if it makes some degree of noise, it's not like I'm not losing sleep over it.