Overview of the Problem – Hidden Leak Under the Kitchen Sink

At a property on Blair Road in Glen Waverley VIC 3150, our team at Your Choice Plumbers was called out after the owners reported a small leak under the kitchen sink.

What made this case tricky was that the leak was not obvious at first. There was moisture under the sink, but no clear dripping point, which made it difficult for the owners to tell exactly what was leaking.

This is exactly the kind of issue where homeowners start asking, “why is there water under my kitchen sink but no obvious leak?” or “can a flexi hose leak without bursting?” As an experienced plumber Glen Waverley, we often find that very small flexi hose failures can stay hidden for a while and only show up as unexplained cupboard moisture before they turn into a major flood event.

Initial Checks and Why the Leak Was Hard to Find

We began by checking all visible plumbing components under the kitchen sink to rule out the most common leak points.

We checked:

  • the 50mm sink waste pipe components
  • the double bowl sink connector
  • the trap extension
  • the S-trap
  • the dishwasher water connection at the combi valve
  • the kitchen sink mixer base to make sure water was not bypassing the tap hole from above
  • the hot and cold stop taps
  • the mixer flexi hoses

At first, nothing obvious was dripping or visibly leaking.

That is what made this case unusual. There was clear evidence of moisture, but no immediate sign of the source.

How We Found the Real Leak Source

To isolate the problem properly, we thoroughly wiped the sink cupboard dry and left it for around 10 minutes before returning to inspect it again.

When we came back, we noticed fresh moisture forming on the back of the cabinetry — but still no obvious dripping.

That was the key clue.

Using a torch and wiping the area more closely, we then identified a tiny pinhole leak on the hot water flexi hose connected to the kitchen sink mixer.

The hose was producing a very fine mist-like spray rather than a visible stream of water, which is exactly why the leak had been so difficult to spot.

We showed the owners how this tiny spray was causing the under-sink leak and explained that this type of failure is often missed until the hose deteriorates further.

Early Flexi Hose Failure Warning Signs

Once the leak source was confirmed, we inspected the hose more closely and found clear signs of tea-staining and corrosion.

When we checked with the owners, they confirmed the kitchen tap was more than 15 years old.

That history made the diagnosis very clear.

We explained that they were actually lucky to catch the problem when they did, because the hose was in the early stage of thread failure. At this stage it was only misting, but it was already showing the warning signs that can lead to a sudden burst if left unresolved.

This is exactly why flexible hoses are one of the most important hidden flood risks in residential plumbing.

Mixer Tap Replacement and Preventative Upgrade

Because the existing kitchen mixer was already older and the flexi hose failure was tied directly to the original tap assembly, we recommended full tap replacement rather than trying to patch only the failed hose.

We supplied and installed a new:

Mizu Drift Pull Out Gooseneck Sink Mixer Curve 2 Function Chrome (5 Star) Lead Free

The replacement tap was sourced from Reece Plumbing Burwood.

This gave the owners:

  • a new kitchen mixer
  • new flexi hose connections
  • a more reliable long-term setup
  • removal of the ageing, corroded original components

Compulsory Water Pressure Check Revealed a Bigger Risk

As part of our standard process, we also checked the water pressure to make sure the plumbing system was operating within compliant limits.

The water pressure reading at the time of testing was 740 kPa.

That is well above the 500 kPa maximum referenced under AS/NZS 3500.

We explained to the owners that excessive pressure is one of the biggest contributors to:

  • early flexi hose failure
  • leaking taps and mixers
  • valve wear
  • appliance connection failures
  • insurance concerns where pressure is left uncontrolled

This meant the small flexi hose leak was not just an isolated problem — it was happening in a home already exposed to broader pressure-related plumbing stress.

Pressure Regulating Valve Installation

To bring the property into safer operating conditions, we also installed a:

20mm Zurn right-angle pressure regulating valve

This was fitted at the water meter to reduce incoming pressure to a more compliant and plumbing-safe level.

That upgrade did not just support the new kitchen tap installation — it also helped protect the entire home’s plumbing system from unnecessary pressure strain moving forward.

This is something we often explain on pressure regulating valve jobs, because correcting excessive mains pressure can significantly reduce future plumbing failures across the home.

Outcome and Client Result

  • hidden under-sink leak source found
  • pinhole hot water flexi hose failure confirmed
  • tea-staining and early hose failure identified
  • aged kitchen mixer replaced with new Mizu pull-out gooseneck mixer
  • high mains water pressure confirmed
  • 20mm Zurn PRV installed at the meter
  • immediate flood risk and long-term pressure risk both reduced

The owners were very happy to have found the problem before the hose turned into a full burst, and even happier to have the pressure issue addressed at the same time.

Compliance & Prevention Insight

This case highlights why even a very small under-sink leak should never be ignored.

A hidden mist spray from a flexi hose can be easy to miss, but it often means the hose is already deteriorating and getting closer to full failure. Catching it at this stage can prevent major cupboard damage, internal flooding, and much more expensive repairs later.

It also reinforces why water pressure matters so much. In this case, excessive pressure was placing unnecessary stress on the plumbing system and likely contributing to the failure of the old hose connection.

Compliance with Australian Standards

All work carried out by Your Choice Plumbers is completed in accordance with the relevant plumbing standards, including the pressure requirements referenced under AS/NZS 3500.

In simple terms, this means your plumbing is not only repaired, but also checked in a way that helps reduce flood risk, improve compliance, and protect the rest of the system from avoidable pressure damage.

Our Home Plumbing Experts Approach

As part of our Home Plumbing Experts approach, we focus on both repair and prevention.

We include our complimentary Property Protection Audit with plumbing services to help homeowners understand hidden risks like excessive water pressure, unsafe hot water temperatures, and ageing flexible hoses before they turn into emergencies.

Find out more about our flexible hose replacement Melbourne services.