You can usually tell a pipe has burst because water appears quickly and keeps coming, often with a hissing or rushing sound. Other common signs are a sudden drop in water pressure, wet patches spreading fast on a ceiling or wall, and water running when every tap is off.
A slow drip from a joint is different. A burst tends to release a lot of water in a short time, so it needs quick action.
Sounds and Sudden Water
The clearest sign is water you can see escaping from a pipe, either as a spray or a steady gush. If the pipe is hidden, you may hear it before you see it. Listen for hissing, rushing or a running-water sound inside a wall, under the floor or in the loft when nobody is using any water.
Water dripping through a light fitting or pouring from a ceiling is a strong warning too. Keep well away from any wet electrics and switch off the power only if you can do so safely. A qualified electrician may need to check things before they are used again.
Changes in Taps and Water Pressure
A burst lets water escape before it reaches your taps. Because of this, you might notice taps running weakly, spluttering or stopping altogether. A toilet cistern may also take much longer to fill than usual.
Low pressure on its own does not prove a pipe has burst. It can be caused by work on the mains or a problem in the street. If the drop is sudden and you can also see or hear water where it should not be, a burst is much more likely.
Damage That Appears Quickly
Burst pipes tend to cause damage that grows by the hour, not by the week. Look for a ceiling that is sagging or bulging, paint that is bubbling, carpets that are suddenly soaked, or water pooling under kitchen units.
After a cold spell, check lofts, garages and outside walls. A pipe can split while frozen but only start leaking once the ice melts, so a burst may show up a day or two after the cold weather has passed.
What to Do Once You Spot the Signs
Turn off the water at your stop tap as soon as you can. Thames Water says your stop valve is usually under the kitchen sink, though in some homes it can be elsewhere. Then open the cold taps to drain the water left in the pipes, and move valuables away from the wet area.
Take a few photos of the damage before you start clearing up. They can help later when you talk to your landlord, a plumber or your insurer.
Once the water is off, the next step is getting the burst pipe repaired so the split section can be replaced and the supply safely restored. Until then, try not to turn the water back on to test it, as this can make the damage worse.