Low water pressure at home — causes and fix
Before you call a plumber and assume the worst about your pipework: most 'low water pressure' cases come down to a simple clean, or a valve someone closed and forgot to reopen. The key is to work out one thing first — is it a single tap, or the whole house? Everything follows from that.
The problem
Water runs weakly or splutters, the shower has dropped to a feeble spray, and filling the washing machine or heater takes forever. Sometimes it's only the hot water, or only the cold, or both together — and that detail matters a lot for the diagnosis.
Likely causes
A limescaled tap aerator or showerhead (the number one cause for a single tap)
Our water is 'hard' — full of calcium salts. Over time that scale builds up on the little mesh screen in the tap tip and on the holes of the showerhead, and chokes them off. If only one tap is weak and the rest are fine, this is the first thing to check — and it clears with a vinegar soak in a quarter of an hour.
A closed or half-open valve
Under every sink and basin there's a small angle valve, plus a main valve for the flat. Sometimes someone closes one partway after a repair or a clean and forgets to open it fully again. If the pressure dropped suddenly right after some plumbing work, check the valves first — you open them by hand in a second.
A low roof tank, or its outlet filter clogged
Most homes here run off a rooftop tank that feeds the house by gravity — meaning your 'pressure' is really the height of the tank above the tap. If the tank is empty or half-full, pressure drops across the whole house. And the tank outlet has a small filter that scales up and chokes the supply to the entire home.
An airlock in the pipes
After the mains is cut and comes back, or after any work on the pipes, a trapped air bubble can stop water flowing properly — you get a spluttering spray with a gurgling sound, often on the hot side. It clears by opening taps and bleeding the air out.
Old corroded galvanised iron pipes
Older homes have galvanised iron pipes, and over the years they rust and scale up from the inside until the bore narrows like a furring artery. Here the weakness is house-wide and gets worse year on year, and no clean will fix it — it needs a plumber to replace the pipework.
A weak or failed booster pump (in buildings that have one)
Some buildings and upper floors have a pump that boosts the pressure. If the pump isn't running — power off, a blown fuse, or a fault — the pressure drops back to its natural weak level. You can check it has power and is running, but repairing or replacing it is a plumber's job.
Fix it — step by step
- Work out: one tap, or the whole house?Go round the house: open the kitchen tap, the basin, the shower, the bath. If only one is weak and the rest are strong, the problem is local (that tap's aerator or valve). If everything is weak, the problem is at the source: tank, pump, main valve, or pipes.Also test: is only the hot weak, or the cold too? If it's only the hot, check the water heater, its inlet valve, and the showerhead.
- Unscrew the tap aerator and soak it in vinegarAt the tap tip is a screw-on piece (the aerator). Turn it anticlockwise by hand; if it's stiff, use an adjustable spanner with a cloth so you don't scratch the chrome. Inside is a small mesh, usually clogged with scale.If you run the tap with the aerator off and the flow is strong, the aerator is definitely your problem.
- Soak the scaled parts in white vinegarPut the aerator and the showerhead in a cup of white vinegar for an hour or two to dissolve the scale, then scrub with an old brush and rinse. For a showerhead you can't remove, tie a bag of vinegar around it and leave it hanging overnight.Vinegar dissolves scale without harming the chrome. Avoid sharp tools — they widen the holes and wreck the spray pattern.
- Check every valve is fully openCheck the angle valve under the sink and basin (turn anticlockwise to the stop), and the main valve for the flat (usually at the water inlet or in the laundry area). Especially if there's been any recent plumbing work.A half-open valve feels exactly like a big problem — but it's the easiest fix in the world.
- Check the roof tank and clean its outlet filterGo up to the roof and look at the water level in the tank — if it's low or empty, the problem is the supply or the float, not your pipes. Then close the tank outlet, unscrew the small filter at the outlet, and clean off the scale and sediment.If the tank empties fast or won't refill, check the float valve — it may be stuck, or the municipal supply may be weak during daytime hours.
- Bleed the trapped air from the pipesOpen the lowest tap in the house (usually the ground floor or garden) fully, and leave it running until the water comes out steady with no spluttering or noise. Then open the other taps one by one, from lowest to highest, until all the air is out.Airlocks are common after the mains is cut to the area or after any pipe work — they're harmless and clear in minutes.
- Check the pump (if there is one) has power and runsIf your building has a booster pump, check it's switched on, has power, and its breaker is up. Listen for it running when you open a tap. If it's dead, check the breaker and fuse.If the breaker trips whenever the pump runs, or it runs oddly without raising the pressure, stop — that's a plumber or electrician's job.
Tools & parts you'll need
When to call a professional
Call a plumber if: the pressure is weak across the whole house and it turns out to be old corroded pipework that needs replacing; you need a booster pump fitted or replaced; you need a pressure regulator installed; or the problem is on the municipal side, at the meter or the main connection. And don't try to open a pipe inside a wall, or work on the pump's electrical connection yourself — leave those two parts to the specialists.
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How do I tell if it's one tap or the whole house?
Go round and open every tap one at a time. If only one is weak, the problem is local — its scaled aerator or its valve. If everything is weak, the problem is at the source: the roof tank, a pump, the main valve, or the pipes. This is the first and most important step before anything else.
Why is the water pressure weak on the top floor of the building?
Because your pressure comes from the height of the roof tank above you, and the top floor is closest to the tank — less height means less pressure. On upper floors or in tall buildings the usual fix is a pressure-boosting pump, which is a plumber's job. Raising the tank higher or fitting wider pipes to it also helps.
The hot water is weak but the cold is strong — why?
Usually it's the water heater or its inlet valve (half-closed or scaled up), or the showerhead is furred on the hot side. Check the heater's inlet valve first, then soak the showerhead in vinegar. If you have a central heater, it may have scale deposits inside that need flushing.
The shower has suddenly dropped to a weak spray — can I fix it myself?
Yes, and it's one of the easiest fixes going. Unscrew the showerhead and soak it in white vinegar for an hour to dissolve the scale blocking the holes, then scrub and rinse. If it doesn't come back to full strength, a new showerhead is cheap and fits in a minute.
After the mains came back to the area, the flow splutters with an odd noise — why?
That's an airlock — a trapped air bubble that got into the pipes when the supply emptied and refilled. Open the lowest tap in the house fully and leave it until the water runs steady and quiet, then open the others from lowest to highest. It clears in minutes with no tools.