Apartment Mystery Solved
February 24, 2026
Source: Reddit
The first time I noticed a glass bottle on the floor of my apartment with a thin tube connected to the back of the wall, I thought it had been installed by some enterprising DIYer or was a peculiar feature of the building that no one bothered to explain. Later, I discovered it is a skvallerrör (tell-tube) leak detection system. This is a simple method for catching water leaks when they occur, before they create problems in the walls.
How It Works
A skvallerrör (tell-tube) system creates an escape route for water to appear while a leak remains concealed behind the wall. When there is a leak in a pipe or connection behind the wall, water will follow the tube until it appears at a location where you can visually identify the problem. This system allows you to identify leaks early. Consequently, water cannot soak into the structure and create problems which may not be identified until much later.
Why Sweden Uses This System
When a slow leak occurs in an apartment, water does not remain confined to the area surrounding the leak. Instead, water can migrate through the walls into floors, ceilings and adjacent apartment spaces. In Sweden, the emphasis is placed upon making leaks visible as quickly as possible to minimize the amount of damage created by a leak, and to allow for timely repair. While the skvallerrör (tell-tube) system does not stop leaks from occurring, it helps to prevent undetected leaks from occurring.
Tube And Bottle
Most skvallerrör (tell-tube) systems have outlets that are located on the floor where the leak is most likely to occur. Many building managers also install a glass bottle as a catch container to collect water when a small leak occurs. A glass bottle has many advantages including:
- They provide immediate evidence of a small leak occurring.
- They eliminate the possibility of finding “mystery” puddles on the floor.
- They provide a clear visual indication of a leak occurring to maintenance personnel.
If water is observed accumulating in the bottle, then there is likely a leak somewhere further upstream in the plumbing system.
Top Floor Only?
I have found that seeing a skvallerrör (tell-tube) system located only on the top floor of a multi-story building is generally due to either the original construction of the building or the fact that the building was renovated in stages. Most common causes include:
- Plumbing piping routes were not constructed in a similar manner on each floor.
- Different renovation periods with varying building codes and standards resulted in pipes being run to a tell-tube outlet on a specific floor.
- There is some aspect of the building design which made it more logical to locate the visible outlet on the particular floor.
What To Do If It Drips
If the bottle is dry, the skvallerrör (tell-tube) system is functioning normally. However, if you do observe water accumulating in the bottle:
- Take a photograph (including the date if possible).
- Do NOT simply drain the bottle and disregard the issue.
- Immediately report the issue to the building management/landlord.
While a slow leak may seem minor, it can result in significant structural damage over time if left unchecked.