Damp ceiling under the bathroom? Water on the floor outside the shower? Tiles that stay wet long after the shower's off? Shower leaks are one of the most common — and most expensive-if-ignored — plumbing problems in Melbourne homes. Prime Plumbing & Gasfitting diagnoses and repairs shower leaks across Melbourne. We identify whether it's the mixer, the waste, the screen seal, or a failed waterproofing membrane — and tell you up front whether it's a plumber's job or a waterproofer's.
Shower leak diagnosis is more involved than most fixture repair. The water source could be at the mixer, the waste, the tile/screen interface, the membrane, or a supply line in the wall cavity — and the visible damp rarely shows directly under the leak (water tracks through framing before showing). Confirming which it is requires methodical isolation testing and sometimes acoustic or thermal detection equipment. Repair work on the supply or waste side requires a BPC-licensed plumber and a Compliance Certificate.
The waterproofing membrane (the rubber-like layer behind the tiles in a wet area) is a separate trade — licensed waterproofers handle membrane replacement. We identify whether that's the cause and refer to a waterproofer if it is, rather than billing for plumbing work that won't actually solve the problem.
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Supply-line repair, mixer replacement, waste pipe repair all comply with AS/NZS 3500.1 (water service) and AS/NZS 3500.2 (sanitary plumbing and drainage). Tempering valve at the unit limits hot water at the shower head to a maximum of 50°C as required by Victorian regulation.
Plumbing work above the threshold gets a BPC Compliance Certificate lodged with the Plumbing Industry Commission. PDF emailed to you with the invoice. Verify any plumber's licence at vba.vic.gov.au before booking.
Bathroom waterproofing membranes must comply with AS 3740 (Waterproofing of Domestic Wet Areas). If we identify membrane failure as the cause, we refer to a licensed waterproofer for the membrane replacement — that's a separate trade qualification and outside our scope of work.
On the booking call we ask where you're seeing the damp (above the shower, beside it, on the ceiling below), how old the bathroom is, and whether the damp is constant or only when the shower is in use. Constant damp suggests a pressurised supply leak; intermittent damp suggests waste or membrane.
On arrival we run isolation tests (turn the water off, wait, check meter; turn off only the shower side, repeat; run the shower without water flow; run with water flow). The pattern of when the damp appears or stops tells us which side of the system is failing. Where needed we use acoustic detection in the wall cavity behind the shower.
If it's a plumbing leak (mixer, waste, supply line), we quote the plumbing repair in writing on-site. If it's a membrane failure, we tell you it's not plumbing and refer you to a licensed waterproofer (we don't bill for plumbing work that won't fix the actual cause). Sometimes it's both — supply leak that's been letting moisture into the cavity AND membrane failure that's accelerating it. We quote the plumbing side and coordinate with a waterproofer for the membrane.
Plumbing repair scope varies — a mixer cartridge replacement is a 30-minute job; a supply-line leak in the wall cavity needs an access hole through plaster, sectional pipe repair, pressure test, and re-finish coordination. We quote each component clearly so you know what's included and what's separate (e.g. plaster make-good is usually a separate trade).
BPC Compliance Certificate lodged on plumbing repair work above the threshold. Photos of the diagnosis (acoustic readings, thermal images, leak point location) emailed to you with the invoice. Useful for insurance claims if the leak has caused water damage that you're claiming for separately.
Information you can collect before the visit speeds up diagnosis and gives us a clearer picture before we arrive.
Is the damp constant, or does it only show after someone showers? Constant damp = pressurised supply leak. Intermittent (showers up, dries between) = waste leak or membrane issue. This single observation usually narrows the cause significantly.
Before-and-after-shower photos of the damp area help us see how it changes through use. Mark the date and time on each photo. If the damp is on a ceiling below the bathroom, photograph the ceiling and the bathroom floor at the same time.
How old is the bathroom (last renovation date)? Bathrooms over 15 years old start running into membrane end-of-life. Bathrooms under 5 years should not have a membrane failure — if they do, it's a workmanship issue and may be covered by builder's warranty.
Clear bathroom of bath mats, storage on the floor, and shelving from the wall behind the shower. If the suspected leak is on a ceiling below, clear the room below for ceiling inspection access.
Run the damp through one diagnostic question first: does the damp grow only after someone uses the shower, or is it constant regardless of use? Constant = plumbing supply leak. Only-after-use = waste leak or membrane failure. The plumber confirms which on the on-site diagnostic.
Depends entirely on the cause. Mixer cartridge replacement is a small visit. A supply-line leak in the wall cavity (access through tile or plaster, sectional repair, pressure test) is more involved. Membrane failure is a separate trade (waterproofer), so the cost varies further. We quote in writing first after diagnosis so you know the actual scope before any work starts.
Generally yes for the consequential water damage (carpet, ceiling, paint). The plumbing repair itself is usually classed as maintenance and not insurable. Membrane failures are typically classed as wear-and-tear and not covered. Each policy is different — check yours.
5-10 years on a quality residential mixer in normal use. Properties with chronic water hammer or high mains pressure see cartridges fail sooner. If your shower drips slightly when fully off, or the mixer feels stiff turning, the cartridge is on its way out.
The flexible braided supply hoses behind sinks (and sometimes washing machines) have a finite service life and burst when they fail — sometimes catastrophically. They're not specific to showers, but the same supply network often has flexihoses to other fixtures. If yours are over 10 years old, we recommend replacement during any wet-area service visit.
Pressurised supply leak (constant damp) — urgent. Water keeps pumping in until shut off. Membrane failure or waste leak (only-after-use damp) — less urgent in any single instance, but cumulative damage is significant. Don't ignore for months. The eventual repair scope grows with how long the leak runs.
It removes the cause, but the mould already growing on plaster, framing, or under tiles needs separate remediation. For surface mould on accessible walls, a basic clean and ventilation usually handles it. For mould inside cavities or behind tiles, you may need a mould remediation specialist after the leak is fixed.
Shower screen leaks (water escaping at the base of the screen onto the bathroom floor) are usually a sealant issue rather than a plumbing issue. We can replace the silicone sealant on the screen base, but for major screen-frame failures or replacement, a glazier or bathroom specialist is the right trade. We'll tell you which on diagnosis.
