Flexi Hoses: The Quiet Cause of Most Household Water Damage

There is a braided silver hose under your kitchen sink, under every basin, behind the toilet and behind the washing machine. Most people have never looked at one. Insurers see them constantly, because when one lets go it does not drip. It delivers mains pressure water into a cupboard until somebody comes home.

We were called to a house in Murrays Bay where water was coming through a bedroom ceiling and mould was forming in the wardrobe below. The source was the toilet directly above. Both the fill valve and the flexible supply hose feeding the cistern were leaking, and had been for long enough to soak the ceiling.

What is a flexi hose, and where are mine?

It is the short flexible hose that connects a fixture to the rigid pipework in the wall or floor. A rubber inner tube, a woven stainless steel braid around it, and a crimped fitting at each end.

Go and look. You will find them in the cupboard under the kitchen sink, under every bathroom basin, behind the toilet feeding the cistern, at the laundry tub, and behind the washing machine and dishwasher. A typical Auckland house has somewhere between eight and fifteen of them, and every one is under mains pressure every second of every day.

There are two kinds, and only one of them can be replaced on its own

This is the part that catches people out, and it is worth understanding before you get a quote.

Some flexi hoses are separate parts. They run from an isolating valve up to the tap tail, with a nut at each end, and if one fails we unscrew it and fit a new one. Cheap, quick, done.

But most modern kitchen mixers and basin mixers come with their hoses already attached. The braided tails are crimped into the body of the tap at the factory, and they are not sold separately. Follow the hose up with a torch: if there is a nut where it meets the tap, it is a separate hose. If it disappears straight into the base of the tap with no fitting, it is part of the tap.

That matters because if the leak is in the tap’s own tail, the repair is a new mixer, not a new hose. There is no way to renew just that section. We get asked to “just change the hose” on kitchen mixers fairly often, and the honest answer is that on that model there is nothing to change.

Braided supply hoses running up to a kitchen tap, alongside the waste trap and disposal

It also changes what a leak under the sink means for your wallet. A weeping separate hose is a small job. A weeping mixer tail means replacing the tapware, so it is worth telling us which one you can see when you ring, and worth having a look before you assume it is trivial.

Why do they fail?

The braid is what holds the pressure, and the braid corrodes. Once enough strands have gone, the rubber inner balloons out through the gap and splits.

What causes it, in the order we see it:

Age, by a long way. This is the number one reason, and it is not a defect. A flexi hose is a consumable part with rubber inside it, and rubber perishes. Fit one and forget about it for fifteen years and it will eventually fail, no matter how good it was or how well it went in.
High water pressure. Auckland mains pressure varies a lot by suburb and by time of day, and unrestricted pressure shortens the life of everything downstream of the meter.
Over-tightening at install. A hose done up hard with a spanner is stressed from day one.
Kinks and tight bends. A hose forced round a corner behind a vanity wears at the bend.

A corroded flexible supply hose removed from behind a toilet

How long do they last, and when should I replace them?

Manufacturers generally talk about five to ten years. Treat the lower end of that as the number that matters, because the warranty on the hose is not the same thing as its safe service life.

Our practical advice: replace them on a schedule rather than waiting for a failure, and do the whole house at once so you are not back under the sink every year. If you have just bought a house and have no idea how old the hoses are, that is a good reason to change them now. A set of flexi hoses is one of the cheapest pieces of insurance in plumbing.

What does one about to fail look like?

Get a torch and look at the braid, especially near the crimped fittings where corrosion starts.

Rust coloured staining or a white crusty deposit on the braid
Individual wire strands broken and standing proud, so the braid looks fuzzy
A visible bulge or a soft spot anywhere along its length
Any dampness or a water mark at the fitting
Green or white corrosion on the brass nuts

Broken strands are the one to act on. Once the braid is failing, the rubber is the only thing holding mains pressure back, and it will not hold for long.

Mine is only weeping a little. Is that urgent?

Yes, more than most slow leaks. A weeping flexi is not a stable condition that will stay the same for months. It is a braid that has already lost strands, and the failure mode from there is sudden.

The Murrays Bay job is the pattern. Nobody saw water in the bathroom at all. It went straight down into the ceiling below and only announced itself as a stain and mould in a wardrobe, by which time the ceiling was wet through. Water from a fixture on an upper floor almost never appears in the room it came from.

Turn the isolating valve off at that fixture, use another one, and get it changed.

Can I replace one myself?

Physically it is a simple part. The failures we get called to are almost always the same three things: over-tightening the nut and crushing the seal, reusing an old fitting that is already corroded, and buying a hose that is the wrong length so it sits kinked.

If you do it yourself, turn the water off at the isolating valve first, hand tighten plus a small nip with a spanner, and leave the hose in a gentle curve with no tension on it. Then check it again the next day. If there is no isolating valve at that fixture, get one fitted at the same time. It turns every future job at that basin into a two minute one instead of shutting the house down.

If you would rather it was done once and done properly across the whole house, give us a call. We cover Auckland and it is a quick job with a very good return.

Common questions

How much water comes out when a flexi hose bursts?

The same as any other mains pipe, roughly fifteen to twenty litres a minute, and it does not stop until somebody shuts the water off. A failure at nine in the morning in an empty house is a full day of that. This is why the location matters so much: a burst hose in a ground floor kitchen is a bad day, and the same hose upstairs is a ceiling.

Does insurance cover a flexi hose failure?

A sudden burst is normally treated as accidental damage, so the resulting damage to floors, ceilings and contents is usually covered, while the hose itself is a few dollars and is not the point. What causes problems is a hose that has clearly been weeping for months, because that starts to look like gradual damage, which most policies exclude. Photograph the failure and keep the old hose.

Should I turn the washing machine taps off when I go away?

It is a genuinely good habit for a long trip, along with shutting the water off at the meter. The washing machine hoses are usually the oldest and least inspected in the house, sitting behind an appliance nobody moves. If you are away for weeks, an unattended failure there is one of the worst water damage scenarios in a home.

Are more expensive hoses actually better?

Better ones use a denser braid and a better grade of stainless, and some come with a marked replacement date printed on the sleeve, which is genuinely useful. But no hose lasts forever, and age catches up with all of them. A good hose fitted properly buys you more years, not permanence, so the replacement schedule still matters more than what you paid.

Is there anything that stops the damage rather than the leak?

Two things help. A pressure limiting valve after the meter takes the stress off every hose, tap and fitting in the house. Beyond that, some homeowners fit a leak detection shutoff that closes the water automatically when it senses flow that should not be there. Neither stops a hose failing, but both change how much water ends up in the building when one does.