Gradual water leaks in your bathroom can quietly cause a lot of damage, which is why learning the warning signs is extremely important.
In this guide, we’ll walk you through the early warning signs and what to do if you have a gradual leak in your bathroom - let’s jump right in.
What are Gradual Water Leaks?
Gradual water leaks are slow, steady escapes of water from pipes, fixtures, or connections that develop over time.
These are very often not noticeable right away, but can lead to long-term damage and be expensive to fix.
Gradual water leaks in the bathroom often occur around pipe joints and worn seals - often starting as a small damp patch and getting worse.
Some common culprits for these leaks include:
-
Pipe joints and connections (water supply and waste pipes)
-
Toilet seals and inlet valves
-
Shower trays and bath seals
-
Basin waste connections
-
Corroded copper or aging plastic pipes
Initially, you might notice smaller signs such as oxidation on copper pipes, a damp patch near a fixture, or a slow drop in water pressure.
At first, these leaks might only lose a few drops an hour, but over weeks and months, the water loss adds up.
How to Notice Gradual Water Leaks in a Bathroom
You can save yourself a lot of money (and headaches) if you spot these gradual leaks before they turn into something serious.
Here are the best methods to use.
Discoloured or Damaged Walls or Ceilings
Check your walls and ceilings first of all.
Water that moves through walls or floors leaves yellow, brown, or copper stains. These spots will start small, and can be harder to notice on walls that are painted.
These areas often feel a bit damp or soft, a sure sign that moisture’s hiding underneath.
Ceilings under bathrooms are especially at risk. If you see stains on a ceiling right below your bathroom, water’s probably getting through the floor. Plasterboard may sag or warp as it absorbs moisture, and sometimes you’ll spot actual drips or bulges that need urgent attention.
Musty or Mouldy Odours
Another common sign is a musty or mouldy smell.
This happens as bacteria start to grow where the water is building up.
Mould and mildew thrive in damp areas and give off an earthy, stale smell. Sometimes you’ll notice the smell even if the bathroom looks clean and dry. The odour may worsen on humid days or after a hot shower.
Black, green, or white mould on walls, ceilings, or around fixtures means there’s too much moisture. Watch corners, skirting boards, and behind toilets - leaks often hide there. Even if you don’t see mould, a musty smell is worth checking out.
Increased Water Bills
An obvious sign that something is wrong is if your water bills are increasing for seemingly no reason.
If this starts to happen, always check for leaks around the house, including in your bathroom.
Slow leaks can cause a lot of water to be lost over time, which can make your bill much higher than you might expect.
Water Stains
Water stains show up as dark patches on floors, walls, or ceilings where moisture has soaked in. These marks usually have uneven edges and might feel cool or damp compared to the rest of the surface.
If you see stains around the toilet base, under the sink, or near the shower, those fixtures are likely leaking. Stains on flooring like vinyl, laminate, or wood mean water’s gotten underneath, risking damage to the subfloor. Tiles can come loose or crack if water messes with the grout or adhesive.
The shape and spot of the stain can help you figure out where the leak is. Streaks running down a wall mean water’s coming from above, while stains spreading sideways suggest a leak at that level moving outward.
Low Water Pressure
If your bathroom taps or shower suddenly lose pressure, you might have a leak stealing water from the system. Maybe the shower feels weak, or it takes ages to fill the sink.
Leaks divert water, so less reaches your fixtures. If only the bathroom has low pressure but the rest of the house is fine, the leak’s probably in the bathroom pipes. If every tap is affected, the main supply line might be the problem.
How to Fix Gradual Water Leaks in a Bathroom
Fixing gradual leaks means finding the problem and using the right fix. Most bathroom leaks come from worn seals, bad pipes, or old caulking that lets water sneak through.
A quick note - if you aren’t confident with DIY, it’s always a better idea to get a professional to take a look.
Identify the Source of the Leak
Start by checking all visible plumbing and connections. Look under the sink, around the toilet base, and along exposed pipes for moisture or stains.
Check for damp spots on walls, ceilings, and floors. Water stains often look like discoloured spots or rings below where the leak starts.
Run water in the bath, sink, and shower, and watch for leaks as you go. Sometimes leaks only show up when certain fixtures are in use. Watch closely where pipes meet fixtures or where sealant meets tiles or tubs.
Turn Off the Water
Before you start repairs, find your main water shutoff valve. It’s usually near the water metre or where the main supply comes in.
Turn the valve clockwise to stop the water. Open a tap to drain the pipes and relieve pressure.
If you’re just fixing a single fixture, you might only need to turn off its local shutoff valve. Most sinks and toilets have these on the supply lines below.
Replace Faulty Parts
Worn washers and loose pipe connections often cause slow leaks. Take out the bad-fitting and look for cracked, hard, or deformed washers or seals.
Buy replacement parts that match your fittings exactly. Quality materials last longer and make future leaks less likely.
Tighten connections with an adjustable spanner, but don’t overdo it - too much force can damage threads or crack fittings. If pipes look corroded or damaged, swap out the whole section instead of patching it up.
Wrap plumber’s tape around threaded connections before putting everything back together. Two or three wraps clockwise usually does the trick for a good seal.
Inspect the Caulking and Grout
Look at the sealant around your bath, shower tray, and sink for cracks, gaps, or places where it’s pulled away. Damaged sealant lets water slip behind fixtures and into the walls.
Check the Toilet
Look at the base of your toilet for water or damp spots - a sign the wax ring seal is failing. This seal keeps water from escaping during flushes.
Make sure the bolts holding the toilet to the floor are snug. Loose bolts can break the seal and cause leaks, but don’t overtighten or you might crack the porcelain.
After Repairs Are Done
Once you've finished the repairs, turn the water supply back on - slowly this time. Keep an eye on every repair point for leaks as the water flows.
Let water run through each fixture for a few minutes. This helps make sure those connections can handle normal water pressure.
When to Get Professional Help
We recommend getting in touch with a professional at any time you don’t feel confident fixing the source of the leak.
This is completely normal, so if you suspect that your bathroom has a gradual water leak, it makes perfect sense to contact a plumber and get them to take a look.
