Quick answer
Low water pressure in a house is usually caused by a partly closed stop tap, a faulty pressure limiting valve, a leak, scale-clogged pipes or fittings, or a problem on the SA Water network. Check whether it affects one tap or the whole house, check for outages, then test your flow at the meter before calling a plumber.
Low water pressure in a house is one of those problems that creeps up slowly or arrives overnight. Either way, a shower that barely wets you and a washing machine that takes forever to fill are hard to live with. The good news is that most water pressure problems have a handful of common causes, and a few simple checks will tell you whether the issue is in your own plumbing or on the SA Water network.
This guide explains how to narrow it down, what SA Water recommends, and when to call a licensed plumber.
Is it one tap or the whole house?
Start here, because it tells you most of what you need to know. Low pressure at a single tap points to that tap or its fitting. Low pressure everywhere points to the supply, a main valve or a leak.
| Symptom | Likely cause | Next step |
|---|---|---|
| One tap or shower is weak | Blocked aerator, clogged shower head, worn tap parts | Clean the aerator or shower head, then call a plumber if needed |
| Hot water weak, cold fine | Tempering valve, hot water unit or valves, scale | Call a licensed plumber |
| Whole house weak, started suddenly | Network outage, main break or a new leak | Check SA Water outages, then check for leaks |
| Whole house weak, getting worse over time | Faulty pressure limiting valve, corroded or scaled pipes, slow leak | Flow test, then call a plumber |
| Weak only when several taps run | Undersized or ageing pipes | Plumber to assess pipework |
| Tank water weak or pulsing | Pump, pressure switch or filter problem | Plumber to check the pump system |
What does SA Water say to check first?
SA Water’s advice is to check, or have a plumber check, your property’s plumbing before anything else. Its list is short:
- make sure the internal stop tap is fully open, if one is installed
- check for a faulty pressure limiting valve (PLV), which are common in homes built after 2005
- look for possible leaks on your property
Next, check for outages. SA Water suggests visiting its faults and outages page for current or planned work in your area. If there’s been an outage nearby, wait for pressure to return to normal once you’re told it’s resolved.
SA Water also points out that pressure naturally varies across South Australia depending on the terrain, whether you’re near the top or bottom of a hill, and the distance from a reservoir, tank or main. Homes high on the Adelaide foothills may simply sit at lower pressure than homes on the plains.
How do I test my water flow?
SA Water describes a simple flow test you can do with your meter.
- Turn off all water-using appliances, such as the washing machine and dishwasher.
- Find your water meter and note the reading on the three red numbers.
- Turn on the front garden tap fully for exactly one minute.
- Take the reading again and subtract the first reading.
If the flow is 27 litres per minute or more, SA Water considers your pressure adequate. If it’s less, SA Water asks you to contact them. If your flow test is fine but taps inside are still weak, the problem is most likely in the plumbing inside your property.
What are the most common causes of low water pressure?
Inside your property, the usual causes are:
- A faulty pressure limiting valve. These reduce high mains pressure to a safe level. When they fail or clog, the whole house suffers.
- Leaks. A hidden leak in a slab, wall or garden line steals pressure and wastes water. A meter that keeps ticking over with every tap off is a warning sign.
- Scale and corrosion. Adelaide’s harder water leaves mineral deposits in aerators, shower heads, valves and older galvanised pipes.
- Partly closed valves. A stop tap or isolation valve that wasn’t fully reopened after work.
- Tempering valve or hot water problems. If only the hot side is weak, look here.
- Undersized pipework. Older homes, extensions and renovations sometimes have pipes too small for modern fixtures.
Could it be a leak?
It’s worth checking, because a leak can drop pressure and run up your water bill. With every tap and appliance off, look at the water meter. If the numbers are still moving, water is going somewhere.
Other signs include damp patches on walls or floors, unusually green or soggy patches in the garden, cracked tiles, or the sound of running water when nothing is on. Reactive clay soils in many Adelaide suburbs move with the seasons and can stress pipes and joints over time.
Hidden leaks are hard to find without equipment. A plumber offering leak detection can use acoustic and thermal tools to locate them with minimal digging. If the leak is sudden and serious, our burst pipe guide explains how to turn off the water main.
What about homes on rainwater tanks?
In the Adelaide Hills and on rural blocks, many homes rely on rainwater tanks and pumps. Low or pulsing pressure on a tank supply usually comes from the pump system rather than the pipes. Common causes include:
- a worn pump or failing pressure switch
- a blocked filter or sediment in the line
- a faulty pressure tank or non-return valve
- a low tank level, especially late in summer
A plumber can test the pump and controls and tell you whether a repair or replacement makes sense. See our rainwater tank pumps page for more.
Can scale and old pipes reduce water pressure?
Yes, and it’s a common story in older Adelaide homes. Adelaide’s water can leave mineral deposits that build up over years inside fittings, valves and pipes. The first places it shows are aerators on taps and the holes in shower heads, which is why cleaning or replacing them often brings a quick improvement.
Older homes may also still have galvanised steel water pipes. Over decades they corrode and scale up on the inside, gradually shrinking the space for water to flow. If pressure has dropped slowly over years and only cleaning the aerators helped a little, ageing pipework may be the cause.
A plumber can assess the pipes and explain options, from replacing a short problem section to repiping part of the house. Renovations are a good time to deal with this, while walls and floors are already open. If you’re planning a kitchen renovation, a renovation specialist such as Kitchen Fox can coordinate with your plumber on new supply lines.
What should I ask the plumber?
Before work starts, it’s worth asking:
- Have you checked the pressure limiting valve and tempering valve?
- Is the problem in the supply pipes, a valve, or a fitting?
- Did you find any signs of a leak?
- What are the repair options, and what does each involve?
- Will I get a certificate of compliance for the work?
Can water pressure be too high?
Yes. SA Water notes that homes built after November 2005 are required to have a pressure limiting valve installed where water pressure exceeds 500 kPa. High pressure can cause hammering pipes, dripping taps and extra strain on fittings and appliances. If you have an older home and suspect high pressure, a plumber can test it and advise whether a valve is worth adding.
When should you call a licensed plumber?
Call a licensed plumber if:
- your flow test passes but pressure inside is still low
- the meter moves with everything turned off
- you suspect a faulty pressure limiting valve or tempering valve
- hot water pressure is weak but cold is fine
- your tank pump is noisy, cycling on and off or not holding pressure
- pressure has dropped steadily over months
Replacing pressure limiting valves, tempering valves and pipework is licensed plumbing work. Safe homeowner checks are limited to cleaning aerators and shower heads, checking the stop tap is open and reading the meter. Visit the Adelaide plumber hub for more on common plumbing problems.
Getting it sorted
If the simple checks don’t explain your low water pressure, send one enquiry through our contact form or call 08 6800 6079. We pass your enquiry to one local plumber, who calls back within 24–48 hours to talk through the problem and quote before any work starts.
Stock photo, for illustration only. This guide is general information for Adelaide homeowners, not professional advice. In South Australia, electrical, plumbing and gas work must be carried out by an appropriately licensed tradesperson, and rules change, so check current requirements with the relevant authority.
