Leaking Shower: Identifying Causes and DIY Repair Techniques

Jan 18, 2024

If you’ve noticed mould building up in your bathroom or damp carpet on the other side of the bathroom wall, there’s a good bet you have a small leak.

Before you go to a plumber and spend a lot of money to fix the issue, here's how you can locate the source of the problem and assess.

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A burst pipe will cause an obvious leak that needs attention. But even a drip, over time, can be just as destructive! Keep an eye out for these telltale signs of leaking shower to prevent water damage:

To identify the source of the leak, start from the water damage, then trace it back.

Step 1.

To pinpoint site of shower leak, you will need to run diagnostic tests. To prepare, stop using shower and allow area to dry for a week.

Step 2.

To determine if leak is caused by pipes or shower floor, apply waterproof tape over floor waste (or plug). Apply tape 30mm up from floor to act as a water level marker. Turn on shower, fill base up to tape. Watch for signs of leak. This step may take up to 2 days.

Step 3.

If water appears, the leak is in the tray/floor section of the shower. For a bathroom installed around 20 years ago, this may be due to a damaged or poorly installed waterproofing membrane. If the leak does not appear and the level remains at the tape marker, go to Step 6.

Step 4

To determine the extent of damage, press against lowest part of shower walls. If wall feels hard after pressure, the damage is not significant, go to Step 5.

Any softness to the wall indicates a major problem, such as rotted timber inside the wall cavity, caused by leaking over time. Termites are attracted to damp timber and may compound the problem. Any structural work and a new membrane must be installed by a qualified professional.

Once all work is complete, re-tile, grout and apply silicone.

Step 5

If the shower floor does not require repair, the leak is coming from the shower wall. To pinpoint, turn off mains, remove shower head with an adjustable wrench, then fit a cap to stop the flow. Turn on mains, open taps and check for leaks. Go to Step 7 if there are no signs.

Step 6

If water appears, the leak is coming from the plumbing behind the shower within the wall. A cracked plumbing fitting is the likely cause. Call in a plumber to repair the pipes inside the wall. If you can access pipes from the rear face of the shower wall (adjoining room or hallway), the tiles will not need to be removed.

Step 7

Look inside your shower cubicle for areas where water may have escaped and entered the wall cavity. Check where the tiles meet the walls, and around taps or shelves for cracks or gaps. Holes or gaps indicate an entry for shower water. The water runs down the walls, then into the gaps behind the taps.

Step 8

To replace grout and sealant, put on safety goggles and with a grout-removing tool, cut and remove old grout between tiles on walls and floor. Sweep away old grout, then vacuum area. Mix grout with water according to packet instructions. In small sections, use a grout float to apply waterproof epoxy grout to tile gaps. Smooth over and remove excess with float. Wipe away excess on tiles with a damp sponge. Allow grout to dry. Wash away residue with water and sponge. Buff tiles dry with a microfibre cloth. Allow surfaces to dry. Apply a new silicone sealant where tiles meet shower walls and doors.

Step 9

To remove shower taps, turn off mains and open taps to release any water in pipes. Unscrew hot/cold caps and tap heads, remove from spindles. Clean tiles around tap openings with methylated spirits and cloth. Turn old tap spindles anticlockwise with wrench. Remove and discard.

Step 10

Attach new spindles to outlets and tighten with wrench. Seal hole with silicone. Clean excess with rag and turpentine. Allow to dry.

Step 11

From tap kit, install new cover plates, tap heads and hot/cold caps by hand. Tighten caps with spanner included in packet.

Step 12

Remove the shower cap. Wrap the plumber’s tape around the shower outlet connector. Attach the shower elbow, then the hose and tighten by hand. Attach the shower head to the hose. Allow the silicone to cure for seven days before use.

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