Low water pressure in the house: what causes it and what to check first

Low water pressure in the house: where to start

Most low pressure problems come down to where the fault sits: in the street, at the meter, or inside the property. Your water supplier looks after the network up to the meter. Logan Water, for example, repairs leaks up to and including the meter, and says leaks on the property side are the owner's responsibility. Redland City Council owns the meter and the pipes that supply it, and the pipes from the meter to the house are yours.

That boundary decides who you ring. A problem in the street is the supplier's to fix. A problem after the meter, such as a leak, a blocked valve or a restricted pipe, needs a licensed plumber. The checks below help you tell the two apart before you pick up the phone.

Work out the pattern first: whole house, one tap, or hot water only

The pattern of the low pressure is the quickest clue to its cause. The City of Gold Coast's guidance puts it simply: if the low pressure is only at particular taps, you have an internal plumbing issue. Whether it came on suddenly or slowly over months also helps. Use this table to narrow it down.

Is it the street or your property? Checking with your water supplier

If the neighbours have low pressure too, the cause is most likely on the supplier's network, and the first step is to check their notices. In south-east Queensland, Brisbane is served by Urban Utilities, Logan by Logan Water, and the Redlands by Redland City Council. Urban Utilities lists current interruptions on its website. Redland City Council publishes planned and unplanned interruptions on its Water Service Interruptions page, and asks you to call 07 3829 8999 if your water is off and nothing is listed.

Maintenance such as hydrant flushing or flow testing can also affect pressure for a while, as can a burst or leaking water main. Redland City Council regularly flushes its water mains, and says outages or maintenance can stir up sediment and leave water cloudy or discoloured for a short time.

Each supplier sets a standard for what should reach your meter. Urban Utilities' metering guidelines state a minimum of 210 kPa at the meter, and its customer charter sets a standard of not less than 21 metres head of water at the property connection in most areas. Redland City Council measures pressure tests against 22 static metres head and 30 litres a minute at the meter. Logan Water's standard is a minimum flow of 20 litres a minute for standard residential connections. If the supply at the meter meets the standard but your taps are weak, the fault is on your side.

Causes on your side of the meter

When only your house is affected, check these four things in your own plumbing. The City of Gold Coast lists problems with your property's plumbing, like a blocked pipe, a concealed leak or a faulty pressure reduction valve, as one reason for water pressure issues.

• A stop tap or meter valve that isn't fully open. These valves control the flow of water into your property.
• A pressure limiting valve that is blocked, damaged or not adjusted correctly. Unitywater says these are generally in the meter box or on the hot water system inlet, on your side of the meter, and are the owner's to maintain.
• A hidden leak. Unitywater notes that leaks can reduce the flow of water reaching your taps, which can lead to low pressure.
• Old galvanised pipework that has corroded. Unitywater says a house built before 1960 is highly likely to have galvanised pipes, and that corrosion can cause a blockage.

If you think a leak is to blame, our guide on how to find a water leak walks through the signs room by room.

When only the hot water pressure is low, the fault is on the hot side

If the cold taps run well but the hot is weak, the problem sits between the cold supply and the hot outlets. Pressure limiting valves are generally fitted in the meter box or on the hot water system inlet, and a blocked or restricted one can cause low pressure. The hot water system also needs enough supply pressure to work as designed. Rheem's guide for one range of electric storage heaters says supply pressure should be greater than 350 kPa for true mains pressure performance, so check the manual for your model.

Repairing or replacing valves on the hot side, such as a pressure limiting valve, is regulated work for a licensed plumber. Our guide to tempering valves and TMVs explains what each one does. If the hot water is gas, any work on the appliance itself is for a licensed gasfitter. If you're in the Redlands, see our Victoria Point hot water services.

Homes on rainwater tanks and pressure pumps

On a tank-fed property, a pump and pressure vessel do the work that mains pressure does in town, so the supplier's network has nothing to do with your pressure. When the pressure drops on tank supply, the pump and pressure vessel are the first things to check, not the street.

Some homes run on mains and tank together with a switch-over device. Installing, removing or replacing an automatic switching device for a rainwater tank is regulated minor work in Queensland, so it needs a QBCC licensed plumber. We service rainwater tanks, pumps and their connections.

Safe checks you can do yourself

There are a handful of low pressure checks a homeowner can safely do before calling anyone. None of them involve taking valves apart or cutting into pipes.

1. Check with the neighbours, and look at your supplier's outage and works notices.
2. Make sure the stop tap at the meter is fully open. Don't touch the meter itself. Redland City Council notes that interfering with a water provider's infrastructure, including the meter, without written consent is an offence.
3. Do a bucket test at the tap nearest the meter, usually the front garden tap. The City of Gold Coast suggests timing how long a 9 litre bucket takes to fill with the tap on full: if it takes a lot longer than 30 seconds, pressure may be low.
4. Check whether the low pressure is worse in the morning and evening, when demand on the network is highest.
5. Clean the aerator on a weak tap and the shower head. Replacing a shower head is unregulated work in Queensland, so you can do it yourself.
6. Do a meter leak test. Turn off all taps, appliances and irrigation, note the meter reading, wait at least an hour without using water, then read it again. Logan Water says a changed reading could mean a leak.

Photograph the meter readings and any damp patches. That record is useful when you call a plumber.

What a plumber tests, and what affects the job

A licensed plumber narrows down where the pressure is being lost: in the supply to the meter, at a valve, or somewhere along the pipework. Where a leak is likely, we use electronic leak detection before anything is cut open, so only the necessary spot is opened.

What affects the size of the job:

• Where the fault is: a valve in the meter box is quicker to reach than a pipe under a slab.
• Access to the pipework, including paths, decks and garden beds over the line.
• The pipe material and its age, since older galvanised pipe can corrode inside.
• Whether a hidden leak has to be found first.

Repairing a broken pipe and replacing a fitting are both regulated work in Queensland, so they need a QBCC licensed plumber. You can check any plumber's licence with the QBCC on 139 333.

When to call a licensed plumber

Call a licensed plumber when the low pressure is only at your house and the safe checks above don't explain it. Most plumbing work in Queensland is regulated and needs a QBCC licensed plumber, and a pressure reduction valve needs a licensed plumber to repair or adjust it. If water is running somewhere it shouldn't, turn it off at the stop tap and see our guide on what to do when a pipe bursts.

Jim Monger Plumbing and Gas is a family-operated plumber based in Victoria Point, working under QBCC licence 15504687 and gas licence L90908. For low pressure, leaks and valve faults, see our general plumbing services or call 0418 871 269.