Water pressure dropped off? Let us find out why.

Low water pressure is one of the most common things people ring us about. Sometimes you sort it out yourself in five minutes. Sometimes it needs a plumber. Either way you can usually work out which one you have got before anyone comes out, and here is how we go about it.

First, is it pressure or flow?

People say "low pressure" when they mean one of two things. Pressure is the force behind the water. Flow is how much water actually comes out over a given time. A tap can have plenty of pressure and still trickle if something downstream is choking it, and those two problems get fixed differently. You do not need to be precise about it, but knowing the difference helps when you describe what is happening over the phone.

Is it one tap, or the whole house?

This is the most useful check you can do, and it costs nothing. Walk around and run a few taps and showers, hot and cold. One weak fixture means the problem is at that fixture. Everything weak means the problem is upstream on the supply side. That single answer rules out most of the list below.

If it is just one tap or shower

When it is a single fixture, the usual suspects are:

• A clogged aerator. The little screen on the end of the tap collects mineral build up. Unscrew it, clean it out, and the flow often comes straight back.
• A scaled up shower head. Same problem as the aerator. Soak it in vinegar overnight or replace it.
• A worn tap cartridge or washer. The internals wear and start restricting flow. A new part fixes it.
• An isolation valve that is not fully open. The small valve under the sink or behind an appliance gets knocked, or left half shut after other work.

If it is the whole house

When every tap is weak, the cause is further up the line:

• The main stop tap is not fully open. After any plumbing work it sometimes gets left partly closed. Check it is wound all the way on.
• A failing pressure limiting valve. Most homes have one keeping the incoming pressure at a safe level. They wear out, and when they go the pressure drops off everywhere at once.
• Old galvanised pipe. In older homes the steel corrodes and narrows from the inside, which strangles the flow. You often get discoloured water with it.
• A leak on the line. Water getting out before it reaches your taps shows up as a pressure drop.
• The mains itself. Street pressure varies by area and it dips at the busy times, morning and evening.

Canberra things worth knowing

Canberra's water network, run by Icon Water, delivers different pressures depending on which suburb you are in and how high up the hill you sit. Homes on higher ground, or at the end of a supply run, get less pressure to start with, and it drops further at peak times. Put that together with the ageing pipework in the older inner suburbs and you can see why we get so many pressure calls here.

What you can check yourself before calling

A few quick checks before you get anyone out will either solve it or save the plumber half an hour:

1. Work out whether it is one fixture or the whole house.
2. Clean the aerator on the affected tap, or the shower head.
3. Check the main stop tap and the tap at your water meter are wound fully open.
4. Ask a neighbour whether theirs is low too. If it is, the problem is on the mains, not in your house.
5. Note whether it dropped off suddenly or crept up on you over months. That matters, for the reason below.

When it is time to call a plumber

Call us, or any licensed plumber, if:

• The pressure dropped suddenly across the whole house. That can mean a burst or a leak, and you could be losing water the whole time, so do not sit on it. If you think it is a burst, read our guide on when to call an emergency plumber next.
• Only the hot water is weak. That usually puts the fault at the hot water unit or one of its valves.
• The pressure is still poor after the checks above.
• The water is discoloured as well as weak, which points to corroded pipe.

You do not have to live with a bad shower. If you have had a go and it is still not right, give us a ring and we will work out what is behind it.