One weak tap is actually good news. It rules out the mains, the meter and your whole-house pipework, and narrows the search to the last metre of plumbing before the spout. Here is the order to check things in, starting with the two you can do yourself in ten minutes.
Single-outlet pressure triage
| Check | How | If this is it | Cost |
|---|---|---|---|
| Aerator or shower head clogged | Unscrew it, look for grit and scale | Rinse or soak in vinegar, refit | Free |
| Isolation valve partly closed | Find the mini stop under the sink or at the cistern, open fully anticlockwise | Full flow returns immediately | Free |
| Kinked or pinched flexi hose | Look under the sink for a tight bend in the braided hose | Hose needs re-routing or replacing | $20 to $40 a hose at trade, plus fitting |
| Blocked mixer cartridge | Cold fine at other taps, this mixer weak on both hot and cold | Cartridge clean or replacement | $80 to $180 plus parts |
| Hot side only weak at this outlet | Scale or debris in the hot line or tempering path | Licensed diagnosis | Quote on inspection |
| Weak at several outlets | Not a single-tap problem, see our low water pressure page | Whole-house diagnosis | Quote on inspection |
Is it just a blocked aerator or shower head?
Start here, because it is free and it is the most common answer. The aerator is the small mesh insert screwed into the tap spout, and its fine screen is a perfect net for grit, scale flakes and debris, especially after any mains work in your street or a hot water system replacement, both of which shake sediment loose into the pipes. Unscrew it by hand or with gentle pliers on a cloth, and the evidence is usually right there in the mesh. Rinse it, soak stubborn scale in vinegar for an hour, refit, and test. Shower heads clog the same way and respond to the same vinegar soak. The pattern we notice: if your weak pressure started within days of work on the mains or your hot water system, the aerator is the suspect until proven otherwise.
Could the isolation valve or flexi hose be the problem?
Absolutely, and this is the other free check. Most modern fixtures have a small isolation valve, a mini stop, on the wall or under the bench feeding each tap. They get knocked, they get half-closed during other work and never fully reopened, and a mini stop sitting half shut throttles exactly one outlet while everything else in the house runs perfectly. Open it fully anticlockwise and retest. While you are under there, look at the braided flexi hoses: a hose installed with a tight kink, or twisted during a tapware change, pinches flow permanently. A kinked flexi is not just a pressure problem, it is a stressed hose, and stressed flexi hoses are the number one burst risk in modern homes, so we replace rather than straighten them, at $20 to $40 a hose at trade prices plus fitting.
Why is my mixer tap weak on both hot and cold?
When a single mixer is weak on both hot and cold but the basin next to it runs fine, the blockage is inside the mixer cartridge, the ceramic disc unit at the heart of every modern mixer. Cartridges collect the same grit and scale as aerators but are less forgiving, and the internal passages are small enough that a flake of scale from an ageing hot water tank can noticeably choke flow. Cleaning or replacing a cartridge is a standard tap service for us, at $80 to $180 plus parts, and it is worth doing properly because a forced or badly seated cartridge becomes a dripping mixer within months. If the tapware is a budget import, we will be straight with you: replacement cartridges can be genuinely unobtainable, and a quality replacement mixer sometimes beats a parts hunt.
When does one weak tap mean a bigger problem?
Three situations earn a professional look. First, weak hot only at one outlet, which can implicate scale in the hot line, the tempering valve path, or the first warning of a hot water system shedding sediment; our hot water pages cover where that leads. Second, a tap that has got gradually weaker over months rather than suddenly, which on older Gold Coast homes with galvanised pipe sections can mean internal corrosion narrowing that branch, and that conversation is about pipe replacement, not tap parts. Third, any weak outlet paired with damp, a hissing sound or an unexplained tick on the water meter, because a leak on that branch bleeds pressure exactly this way, and finding it early is the whole point of leak detection, which runs $200 to $500 or more depending on what it takes. One weak tap is usually trivia. One weak tap plus a symptom is a lead worth following.
What should I do right now?
Clean the aerator, open the mini stop fully, check the flexi for kinks. That solves most of these. If flow is still weak, or the hot side only is down, book it in and tell us what you already ruled out.
One tap or shower running weak? Call Hills Plumbing & Gas on 0472 657 042 or book through our Leaking Taps & Toilets service page. Fixed-price tap services $80 to $180 plus parts, Gold Coast wide, QBCC licence 15243081.