It’s worth finding out if the mould is caused by condensation (i.e. warm, humid air hitting a cold surface), or water ingress (i.e. water coming in from outside and making your walls damp). If it’s the former, there are things you can do to reduce the humidity in your house, get more air circulating, or deal with the mould as it arises. If it’s the latter, you really need to get the landlord to fix the problem that is causing water to get into the walls – not only is this a potentially serious structural problem with the fabric of the building that could destroy any investment the landlord has if left unchecked, but anything you do as a tenant may be quite ineffective.

If it is just condensation though, there are things you can try. Condensation happens when the humidity is high enough, and the surface cold enough, for the moisture held in the air to be released onto that surface. Cold air holds less moisture than hot air, so even though the weather forecast might say it’s 90% humidity outside, if the outside air is only 5 degrees C, it will still hold far less moisture than your indoor air at 20 degrees C. So one strategy is to swap out the relatively moist air inside your house for the relatively dry air outside your house. Obviously that incurs a cost – it gets colder in your house, and therefore it costs more to heat your home. The other strategy is to extract moisture from the air inside your house. The most effective way is with a dehumidifier, but it also includes wiping down windows, shower cubicles, etc. and getting the moisture down the drain or out of the house.

• (£100s) Run a dehumidifier to keep the humidity levels to <70% at least. The dehumidifier will be expensive to buy, and running it will also be expensive at today’s electricity prices. (We have a cheap overnight tariff, so we only run it during the “cheap” hours. Still quite expensive though.) You’ll find much cheaper options that involve absorbent gels or pellets that will absorb some moisture, but nowhere near enough to make a difference. I’d avoid these if you are already having mould/condensation problems.
• (£30 - £2) Buy a Window Vac and vacuum all your windows, vacuum your shower cubicle after you use it, that sort of thing. Alternatively, a cheap £2 squeegee is fine, but when you use it make sure the water goes outside or down the drain, rather than sitting in the bottom of the shower/windowsill. I.e. squeegee your shower tray too. May sound obvious but apparently not to my family!
• (£5 ish per bottle) HG Mould Spray is amazing at getting rid of mould caused by condensation. If it’s caused by condensation, and you deal with the humidity/condensation afterward, you probably won’t have to reapply it until the following year at worst. That’s been our experience anyway. (If you don’t adequately deal with the condensation then you’ll probably have to do this a few times over the winter, which is unpleasant and awkward with kids as you need to keep them away and ventilate the room well.)
• (FREE!) Open the window in your shower/bathroom BEFORE you start your shower/bath, and leave it open the whole time. Close it when it feels like the temperature is slightly below the rest of the house.
• (FREE!) You can also open windows in the kitchen when you’re boiling stuff – all that moisture has to go somewhere, so better that it goes out of the window. And since cooking will naturally involve warming up a room, you don’t have to worry as much about the heat loss.
• (FREE!) Open your trickle vents above your windows if you have them. It will get slightly colder, but houses/double glazing is usually designed with trickle vents in mind. It won’t magically solve all condensation (probably won’t do much tbh) but it will contribute slightly to better ventilation.

Sounds like you are lucky if you only have a little around the windows in this country.

You can run dehumidifiers in that room to try and suck out some of the ever present moisture during the winter and keep on top of wiping down the windows to remove condensation, particularly in the mornings if it is the room you sleep in.

You can also get those absorbant “dehumidifier” things that will collect and absorb some of the moisture but really it is a losing battle that you just have to try and fight as best you can I have found. You’ll never win xD

We have windows open nearly all the time, mostly upstairs and have just got used to wearing jumpers/hoodies more often.

When the mould gets bad in the worst winters, we use bleach water to kill off and clean and places like the bathroom we repaint every couple of years with another layer of mould suppression.

The worst wall is the back wall of the kitchen, it can get terrible. The management company dug a trench directly against the wall outside and filled it with gravel to help rain water drain away.

The house is an investment to someone. Why not fix things properly? It really pisses me off. It’s always a quick fix/bodge.

We’ve had a question about this in our house which is 100+ years old too. I bought a £5 hygrometer off Amazon, this measurement will tell you the humidity level in the room or wherever you place it. Anything over 65-70% will start to see damp, mould, respiratory conditions and the rest, but it helped me to know exactly what the situation is. Our bathroom needed better ventilation for example as it’s a wet room, same for kitchen. It’s pretty obvious really, you can see moisture on windows but it’s the moisture you can’t see which is what you’re measuring.

Indoor plants love moisture, they can take care of some of the problem. Our kitchen window plant is out of control, very happy plant.

Water in brickwork is really bad. It can start at the base of the brick wall and rise through hydraulic action, or if there’s a loose gutter at the top it only takes a hole under 1mm to be a constant drip which never allows the brick to dry. Also could be the brick pointing, if it’s old pointing cement it might have turned to sand and blown away, so the job of protecting the brick is lost and water could be going inside rather than down the face. This is an easy job but not cheap so better to find a brickie for an assessment. Likewise cracks in render allow water in but not out. You can run round with a sealant tube and it might solve it.

There’s some great suggestions here, if feasible - but if it’s just round the windows, I’d probably just wipe it off and not worry too much. I don’t think I’ve ever lived anywhere where that didn’t happen in at least one room.

Some “mould and mildew spray” from your local “bits and bobs” shop would do the job fine, or sugar soap if it’s really bad. Any general cleaning spray will get it off with a bit of effort.

This only applies if it’s just round the windows and windowsills though - watch out for black mould on/behind the wallpaper, in the walls, in the paint, back of the wardrobe, back of the bed, back of drawers etc - that’s potentially a whole different level of grim. Try and keep your house above 10°C, even at night, that stuff really spreads when the house gets cold.