What Causes Shower Leak?

Showers and bathrooms are some of the most used rooms in our properties. If you don’t identify when a shower alcove is leaking, bigger issues like permanent damage to your property can happen. This article helps to explain some of the reasons your shower might be leaking and what is required to investigate the cause and how to conduct repairs.


The tiles in your shower could be what is causing your shower to leak. This could be the tile on your shower floor or walls. Here is how to tell if this is the cause of your shower’s leak.

To test if the leak is coming from your shower floor, the first thing you will want to do is clean the floor of your shower and let it completely dry. Then, use high-quality duct tape and cover up the drain. The drain will need to be covered by at least 150mm on all sides.

The next step is to use a different water source like a hose or water from another bathroom. Fill up the shower base to the point that the water reaches the level of the threshold or the top of the hob.

By using water from another source, you should be able to make sure the leak is not from the plumbing in the shower. Once your shower is filled with water, it will need to sit. Depending on where your shower floor is, you could see water on a ceiling or subfloor area below.

If you see a leak here, then it’s possible that the problem is with the base of your shower and you need to engage a registered builder. If after 15 minutes you do not see signs of a leak, then your problem is not on the shower floor.


If your shower can drain without leaking, then you might need to see if the leak is coming from the grout between the shower walls and tiles. To see if this is the problem, check out one wall at a time. You will need to start low on the wall and spray or splash water onto an isolated area.

Keep checking for leaks as you work your way up the shower walls, going a couple of feet at a time. You will need to visually inspect the grout before and after you get each section damp. Keep an eye out for missing grout as even a small hole in the grout can be the cause of a leak.

Once you have soaked one wall, go to the next one, all the while checking for leaks. Once you think you have found the source of your leak, repeat the test in that area to be certain you have isolated the leak.

If you find grout missing, regrout that area. Grout is simple to mix and apply once you have scraped out any loose material. If you are not sure how to apply grout it is always advised to engage a qualified tiling contractor or registered bathroom specialist.

Leaking Taps

A common cause of your leaking from your shower could be a leaky shower head or tap. Here is how to tell which one is causing the problem.

If you have a drip that is keeping you up at night or staining your shower alcove, you may be able to fix this by replacing the washer or rubber seal.

If your shower has a single mixer tap, then the springs and gaskets around the inlet holes are probably the issues as they get worn after use. If you have two taps, then the leak could be caused by a washer and the ends of the valve stems. Sometimes but rarely, the ball valve or cartridge on your single mix tap gets nicked or cracked which causes a leak.


To see if it is the drain that is giving you problems, you will want to tape off the drain and let the water flow out. You will also want to check for leaks, and if you see one at this point then the problem is probably with the drain.

Also, keep in mind the shower and tub drains are connected to P-traps like sink drains and these traps can leak. Water can also get into strainers that are not properly connected to the drain and this could be from small breaks or cracks in the bottom of the fixture.

When water leaks from these places, it is usually obvious in the room below or on the bathroom floor as it buckles in the ceiling drywall. Water does not always come from the drain it can also come from rusted water or loose supply connections.

Leaking Pipes

Your leaky shower could also be because of solder connections on the copper pipes of the shower or plastic valves that are not properly installed or are getting old. Usually, valves have a screw-on connection that is not tightened enough.

Even if the connection is tight, they can leak as the shower ages. This is because rust develops causing pinhole leaks at the joints.

You can replace a shower arm or spout, but other repairs will need access to your plumbing. This is why in most cases this job is best left to a professional.

Now that you know the reasons why you have a leaking shower, do these tests we suggested to get to the root of the problem. It is either coming from the drain, tap, shower floor, walls, or a water supply leak. If you do suspect a shower is leaking or if you have tested it using our suggestions and found it to be leaking, immediately engage a qualified plumber or registered builder to further assess the shower and to provide the cost for rectification.

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