Five common causes of falling shower pressure in a Kapiti home — restrictors, cylinder valves, blocked head, partial blockage, and mains pressure changes. What to check first.
A shower that has lost its pressure overnight is almost always one of five things. The trick is knowing which to check first — most homeowners can rule out two of the five in five minutes, which saves money on a diagnostic call-out.
1. Blocked shower head
The most common cause. Mineral deposits and limescale build up inside the holes of the shower head and reduce the open area for water. Unscrew the head and soak it overnight in a 50/50 mix of warm water and white vinegar. Brush the holes with an old toothbrush. If pressure improves once the head is off entirely, you have your culprit.
2. Flow restrictor in the head
Newer shower heads ship with a small plastic or rubber flow restrictor inside the inlet, often coloured red or green. Some can be carefully removed (check the manufacturer guidance) without losing certification — the head will then run at the home’s native pressure.
3. Partially closed isolation valve
Many showers have an isolation valve in the wall behind the cabinet or in the cupboard. If a recent plumbing job has been done — even on a different part of the system — there is a chance an isolation valve was throttled back and not fully reopened. A licensed plumber can locate and check yours in minutes.
4. Cylinder pressure-relief valve sticking
For hot water specifically, a sticking pressure-relief valve on a low-pressure cylinder can drop the available hot-water pressure to the shower mixer. Symptom is a shower that has plenty of cold but limp hot. Replacing a stuck valve is a 30-minute job.
5. Mains pressure change
Less common, but on the Kapiti Coast Council mains pressure does occasionally fluctuate. If the entire house has dropped pressure — kitchen tap, laundry tub, garden hose — the issue is upstream of the home, not inside. The neighbours will usually have the same problem. A call to Kapiti Coast District Council confirms it.
When to call
If steps 1 and 2 have not resolved it, the issue is most likely inside the wall or at the cylinder. Tony will diagnose any of causes 3 to 5 in a single visit. For shower mixers more than 10 years old, replacement is often the more economical fix than internal valve repair.