A leaking flexi hose under the sink might seem like a minor drip, but left unchecked it can cause thousands of dollars of water damage to your cabinetry, flooring, and even the structure of your home. The good news is that replacing a flexi hose is a straightforward job many Kiwi homeowners can tackle themselves — as long as you understand what's involved and when to call in a pro.
What Is a Flexi Hose and Why Do They Fail?
A flexi hose (also called a flexible braided hose or tap connector) is the short, corrugated hose that connects your tap or mixer to the water supply pipes under the sink. They're typically made with a stainless steel braided outer layer and a rubber or polymer inner tube.
Flexi hoses have a limited lifespan — generally around 10 years, though this varies by brand and water quality. Common causes of failure include:
- Age and UV degradation of the inner rubber tube
- Corrosion of the stainless steel braid, especially in humid under-sink environments
- Overtightening during installation, which stresses the fittings
- Kinking from being bent at too sharp an angle
- Poor-quality hoses that don't meet NZ standards
When a flexi hose fails suddenly, it can release the full mains water pressure into your home — potentially hundreds of litres per hour. This is why regular inspection and timely replacement matter.
How to Identify Where the Leak Is Coming From
Before you grab a spanner, take a moment to locate the source of the leak:
- Dry the area under the sink with a cloth or paper towels.
- Turn on the tap and watch carefully — is water dripping from the hose body, from the connection at the tap, or from the connection at the wall/floor valve?
- Check whether the hose itself is bulging, discoloured, or corroded — these are signs it needs full replacement, not just a tighten-up.
- If the leak is at a fitting, sometimes a gentle quarter-turn tighten with a spanner will stop it. Do not overtighten — this can crack the fitting.
If the hose body itself is leaking or visibly damaged, replacement is the only safe option.
What You'll Need
- Adjustable spanner or basin wrench
- Replacement flexi hose (correct length and thread size — measure your old one)
- A bucket and towels
- PTFE tape (thread seal tape)
- Torch
Replacement flexi hoses are available at Bunnings and Mitre 10. Choose a hose that meets AS/NZS 3499 (the standard for flexible hose assemblies) — look for this marking on the packaging. Avoid very cheap, unbranded hoses.
Step-by-Step: Replacing a Flexi Hose
1. Turn Off the Water Supply
Locate the isolating valve on the supply pipe under the sink (it usually has a flat-head screw slot — turn it 90° to close). If there's no isolating valve, you'll need to turn off the water at the toby (water meter) outside. Turn on the tap above to release pressure and drain residual water.
2. Disconnect the Old Hose
Place a bucket under the hose. Using your spanner, unscrew the hose from the tap tail (above) and from the isolating valve or supply fitting (below). Note the thread direction — most are standard right-hand thread (lefty-loosey).
3. Check the Fittings
Inspect the tap tail and valve threads for damage or corrosion. Clean away any old PTFE tape or debris.
4. Fit the New Hose
Apply a couple of wraps of PTFE tape to any male threads if required (some hoses have fibre washers instead — check the instructions). Hand-tighten the hose connections first, then snug them up with a spanner — firm but not forced.
5. Turn the Water Back On and Check
Slowly open the isolating valve, then check all connections carefully for drips. Run the tap for a minute and re-check. Dry the area and leave a paper towel underneath overnight as a leak indicator.
Is Replacing a Flexi Hose Restricted Plumbing Work?
In New Zealand, plumbing work is regulated under the Plumbers, Gasfitters, and Drainlayers Act 2006. Replacing a flexi hose that connects to an existing, accessible isolating valve is generally considered maintenance work that a homeowner can do on their own home.
However, if the job involves:
- Installing or moving an isolating valve
- Working on the supply pipes themselves
- Any work on a rental property (where different obligations apply)
…then you'll need a licensed plumber. Check licensing at the Plumbers Gasfitters & Drainlayers Board.
For rental properties, landlords should also be aware of obligations under the Healthy Homes Standards, which include maintaining plumbing in good working order.
When to Call a Professional
Call a licensed plumber if:
- The hose has burst and caused significant water damage
- There is no isolating valve under the sink (one needs to be installed)
- The tap tail or supply fitting is corroded or damaged
- You're not confident working with pressurised water systems
- The property is a rental and you're the landlord
- The leak is coming from inside the wall or floor
A qualified local plumber can also inspect all your other flexi hoses at the same time — a worthwhile precaution in older homes. Find a trusted tradesperson on tradedirectory.co.nz.
Preventing Future Flexi Hose Failures
- Inspect hoses annually — look for rust, bulging, or cracking
- Replace hoses proactively every 8–10 years, or sooner if they show wear
- Ensure hoses are not kinked and have a gentle curve
- Consider fitting a water leak detector under the sink — these are inexpensive and available at most hardware stores
- BRANZ recommends regular home maintenance checks, including under-sink plumbing, as part of good building upkeep