How to Check for Hidden Water Leaks in Your Home

Hidden water leaks are one of the most common and costly  plumbing problems homeowners face. Unlike obvious leaks from a dripping tap or burst pipe, hidden leaks can go unnoticed for weeks or even months, causing structural damage, mould growth, and unexpectedly high water bills.

In this guide, we’ll explain how to spot the signs of a hidden water leak, how to check your home step by step, and when it’s time to call a professional plumber.

Why Hidden Water Leaks Are a Serious Problem

Even a small, concealed leak can waste thousands of litres of water each year. Over time, this can lead to:

• Damp walls and ceilings

• Mould and mildew growth

• Rotting timber and flooring

• Damage to plaster, paint, and brickwork

• Increased water bills

• Reduced water pressure

Catching leaks early can save you money, stress, and major repairs.

Common Signs of a Hidden Water Leak

Before checking specific areas, look out for these warning signs:

1. Unexplained Increase in Water Bills

If your water usage hasn’t changed but your bill has gone up, a hidden leak could be the cause.

2. Damp Patches or Discolouration

Brown stains, bubbling paint, or peeling wallpaper on walls or ceilings often indicate leaking pipes behind them.

3. Musty Smells

Persistent damp or mouldy smells, especially in cupboards or under stairs, can signal trapped moisture from a leak.

4. Low Water Pressure

A sudden or gradual drop in pressure may be caused by water escaping somewhere in the system.

5. Sounds of Running Water

Hearing water running when no taps or appliances are in use is a classic sign of a hidden leak.

Step-by-Step: How to Check for Hidden Water Leaks

Step 1: Check Your Water Meter

This is one of the easiest ways to confirm a leak.

1. Turn off all taps and water-using appliances.

2. Locate your water meter.

3. Take a reading and wait 30–60 minutes without using any water.

4. Check the meter again.

👉 If the reading has changed, you likely have a leak somewhere in your home.

Step 2: Inspect Under Sinks and Cabinets

Leaks often hide in places that aren’t regularly checked.

• Look under kitchen and bathroom sinks

• Check around pipe joints and valves

• Feel for dampness or water marks

• Look for mould or warped wood

Step 3: Examine Walls, Ceilings, and Floors

Pay close attention to:

• Ceilings below bathrooms

• Walls near radiators or pipe runs

• Floors that feel soft, warped, or uneven

Any unexplained damage could point to leaking pipework.

Step 4: Test Your Toilet for Silent Leaks

Toilets are a common source of hidden leaks.

Simple test:

1. Add a few drops of food colouring to the cistern.

2. Wait 15–20 minutes without flushing.

3. Check the toilet bowl.

If colour appears in the bowl, your toilet is leaking and wasting water.

Step 5: Check External Areas

Hidden leaks aren’t always indoors.

• Inspect outdoor taps

• Look for unusually damp patches in your garden

• Check paving or driveways for sinking or pooling water

These may indicate an underground leak.

Areas Most Prone to Hidden Leaks

• Behind bathroom walls

• Under floors

• Inside kitchen units

• Loft pipework

• Central heating pipe runs

• Around boilers and hot water cylinders

Regular checks in these areas can prevent long-term damage.

When to Call a Professional Plumber

If you suspect a hidden leak but can’t locate it, it’s time to call an expert. Professional plumbers use specialist equipment such as:

• Leak detection tools

• Moisture meters

• Thermal imaging

• Pressure testing

This allows leaks to be found without unnecessary damage to your home.

How to Prevent Hidden Water Leaks

• Have your plumbing inspected regularly

• Replace ageing pipework

• Don’t ignore small signs like damp smells or stains

• Insulate pipes to prevent corrosion and freezing

• Fix minor leaks before they worsen

Final Thoughts

Hidden water leaks can be easy to miss but expensive to ignore. By checking your home regularly and acting quickly when you notice warning signs, you can protect your property and avoid costly repairs.

If you suspect a hidden leak and need professional help, contacting a qualified plumber early can save time, money, and damage to your home.