A plumber says I need a pressure limiting valve. Do I?
It's a fair question to ask. A pressure limiting valve, or PLV, is a small brass valve fitted on the water line, usually just after the meter, that keeps the pressure in your home at a safe level. In many Eastern Suburbs homes it's a genuine need, not an upsell, but you shouldn't have to take anyone's word for it. A quick pressure test settles it. Here's what a PLV does, when you need one, how to check, and why hot water systems often need their own valve too.
What a pressure limiting valve does
Sydney Water supplies water at whatever pressure the local mains run at, and in some streets that's well above what household plumbing is designed for. A PLV takes that high incoming pressure and limits it to a set level inside the house. Without one, high pressure wears out tap washers and cartridges, bursts flexi hoses, makes pipes bang, and makes the relief valve on the hot water system drip.
When a PLV is needed
Under the plumbing rules NSW follows, the static water pressure at outlets inside a building shouldn't exceed 500 kPa. If the pressure coming in from the mains is higher than that, a pressure limiting valve is the standard way to bring it down. It's required on new plumbing work where pressure is too high, and it's worth fitting in any home where it is.
Signs pressure is too high
Taps that spray or hammer when turned off, toilets that keep refilling, a relief valve that drips constantly, burst flexi hoses or washing machine hoses.
Signs a PLV has failed
PLVs wear out too. If the problems above appear in a home that already has a PLV, the valve itself may need replacing.
How to know it's genuine
- Ask for a pressure test. A plumber should put a pressure gauge on a tap near the meter and show you the reading. Over 500 kPa means a PLV is justified.
- Ask to see the existing valve. If you already have one, they should show you where it is and why it's not working.
- Get the price first. You should get a fixed price before any work starts, with the reading written on the quote.
If you're unsure about a quote you've been given, we're happy to test the pressure and tell you straight whether you need one.
PLVs on hot water systems
Mains pressure hot water systems are built for a certain maximum pressure. Where the incoming pressure is higher, the maker's installation instructions usually call for a pressure limiting valve or expansion control valve on the cold supply to the heater. If your hot water relief valve drips all the time, missing or failed pressure control is one of the first things we check. See our relief valve dripping page.
Water pressure in southern Eastern Suburbs homes
Pressure varies a lot from street to street. Homes in lower-lying parts of Matraville, Botany, Pagewood and Eastgardens often see higher mains pressure than homes on the ridges, and many older houses have never had a PLV fitted. Our water pressure guide explains more.
Why locals call us
- Local to Matraville and the southern Eastern Suburbs
- Free on-site quotes, with a fixed price before any work starts
- Lifetime labour warranty on our workmanship
- 100+ five-star Google reviews
- Licensed plumbers and gasfitters (Lic. 398171C)
Common questions
What is a pressure limiting valve?
A valve fitted on the water supply, usually just after the meter, that keeps the water pressure inside your home at a safe level.
Is a plumber scamming me if they say I need a PLV?
Not necessarily. Ask them to test the pressure with a gauge and show you the reading. If it's over 500 kPa, a PLV is justified.
What is the maximum water pressure allowed in a house?
Static pressure at outlets inside a building shouldn't exceed 500 kPa under the plumbing rules NSW follows.
Does my hot water system need a PLV?
Often, yes. Mains pressure hot water systems usually need a pressure limiting or expansion control valve where incoming pressure is higher than the heater is rated for.
How long does a PLV last?
Many last ten years or more, but they do wear out. If high-pressure problems come back, the valve may need replacing.
Related help: water pressure guide, water meter guide, relief valve dripping and flexi hose replacement. Local pages: Matraville, Botany, Pagewood and Eastgardens.