A PRV, or pressure reducing valve, is a brass valve fitted to your mains water line that lowers high street pressure to a safe level for your pipes, taps and hot water system. A PRV suits any Sydney home where mains pressure is high, with noisy pipes, dripping taps or a weeping hot water relief valve as the usual warning signs.
This guide covers what a PRV is, the related TMV valves and tundish drain, how to choose one, what installation involves, and what a Sydney plumber charges. It also links to our guides on water hammer and low water pressure.
Key points
- A PRV is a water pressure control valve that reduces mains pressure; it protects taps, appliances and your hot water system from excess pressure.
- A PRV is not a TMV: one controls pressure, the other limits hot water temperature at the outlet to prevent scalds.
- Fitting a PRV is plumber labour at $92–$230 per hour plus call-out of $69–$170, and the valve itself is a modest extra.
- Installing a PRV, or replacing a hot water system, is licensed work, so book a plumber and ask for a Certificate of Compliance.
What is a PRV?
A PRV sits on the cold water main as it enters your property, usually near the meter or the first tap. It holds downstream pressure steady even when the street pressure rises overnight, when demand is lowest.
It is also called a water pressure control valve, and you may see it described as a pressure limiting valve. The label on the body tells you the pressure it reduces to, which is why a 2 bar pressure reducing valve is described by its setting.
- Location: on the cold supply after the meter and before the branches to the house, so every fixture is protected.
- Body: usually brass, with an adjustable spring or diaphragm and a strainer to catch grit.
- Setting: the outlet pressure printed on the label or set by the plumber, read against your hot water unit’s data plate.
- Isolation: a stop tap on either side lets a plumber service or replace it without draining the whole house.
- Compliance: fitted by a licensed plumber to the Plumbing Code of Australia and AS/NZS 3500 (plumbing and drainage).
- Homeowner jobs: you can shut off the water and plunge a toilet at the bowl (how to unblock a toilet), but valve work is licensed.
- Warning signs: noisy pipes, repeat tap leaks and a hot water relief valve that drips or runs often point to excess pressure.
Types of PRV and related valves
| Type | Best for | Strength or lifespan | Price band |
|---|---|---|---|
| Mains PRV (water pressure control valve) | Whole-house protection where street pressure is high | Long life if the strainer is serviced; ask the maker for details | Low to mid |
| 2 bar pressure reducing valve | Setups that need a firm, lower outlet pressure | Fixed or adjustable by model; confirm on the label | Low to mid |
| Adjustable PRV with gauge | Homes that need fine-tuning and easy checking | Gauge lets you spot a failing valve early | Mid |
| TMV valves (tempering or thermostatic mixing valves) | Limiting hot water temperature at the tap or shower | Needs periodic servicing; follow the maker’s schedule | Mid to high |
| Hot water system tap (isolation valve) | Shutting off the water to the hot water unit | Simple and durable, but can seize if never used | Low |
Price bands are relative only. Your plumber should list the model, setting and brand on the quote.
PRV cost in Sydney
| Charge (Sydney, Oct 2026) | Range | Typical |
|---|---|---|
| Plumber call-out fee, incl. GST | $69–$170 | $140 |
| Hourly rate, business hours | $92–$230 | $140 |
| Hourly rate, after hours | $170–$345 | $255 |
| After-hours or emergency visit | $290–$805 | $520 |
| PRV valve supplied (materials) | $80–$300 (indicative — get itemised quotes) | |
| PRV supplied and fitted | $300–$900 (indicative — get itemised quotes) | |
- Access to the main: a valve fitted in a clear meter box takes less time than one buried behind a garden bed or a shed.
- Existing pipework: older galvanised pipes can crumble when disturbed, which adds repair time to a simple valve swap.
- Bundled jobs: fitting a PRV during a hot water system change is cheaper than a stand-alone call-out.
- Water shut-off: finding and testing the main stop tap first avoids a surprise mid-job.
PRV pros and cons
Pros
- Protects taps, toilets and appliances from the wear that high pressure causes over time.
- Reduces water hammer and noisy pipes, which many Sydney homes with high mains pressure suffer.
- Helps hot water systems and relief valves work within their design limits.
- Cuts water use at taps, because less pressure means less flow for the same lever position.
- Gives a licensed plumber a single place to set and check household pressure.
Cons
- Adds a cost and a part that must be serviced, as the strainer can clog with grit.
- A failed PRV can cause low pressure or, in the worst case, let full pressure through unnoticed.
- Set too low, it can make showers weak, especially at the end of a long pipe run.
- It is not a cure for low pressure, which has its own causes (see below).
- Needs a licensed plumber to fit, and an amateur setting can void the warranty.
How to choose a PRV
- Measure your pressure first with a gauge on a tap, because a PRV only helps if mains pressure is genuinely high.
- Read your hot water unit’s data plate for the maximum pressure it accepts, then pick a setting at or below it.
- Match the connection size to your mains pipe, which is why our pipe sizes and types guide is worth a look.
- Choose a brand with local spares from a supplier such as Reece, so service kits and strainers are easy to get.
- Look for WaterMark certification on the valve, and ask the plumber to name the model on the quote.
- Decide about a gauge, since an adjustable PRV with a gauge is easier to check at each service.
How to install a hot water system: PRV, TMV and tundish
Sydney Water says a licensed plumber is needed for replacing hot water systems, so this section explains what the plumber does, not a DIY method.
- Isolate the water and power or gas and drain the old unit, so no one is working on a live system.
- Fit or check the PRV on the cold supply, set to suit the new unit and the house.
- Connect the unit with new flexible hoses and isolation valves, or hard pipe where required.
- Fit the relief valve and run its discharge pipe to a visible tundish.
- Add a TMV where the Plumbing Code of Australia requires tempered water at certain outlets.
- Commission and test, then hand over a Certificate of Compliance and the manufacturer’s paperwork.
| Installed hot water system (Sydney, Oct 2026) | Range | Typical |
|---|---|---|
| Electric storage | $760–$2,850 | $1,700 |
| Gas storage | $1,150–$3,325 | $2,100 |
| Heat pump | $2,850–$5,700 | $4,000 |
Tundish drain installation and PRV discharge
The tundish is the open funnel where the hot water relief valve discharges, so you can see if it runs. Its drain line must fall continuously, stay unblocked and terminate somewhere safe.
- Visible discharge: the tundish must be where you can see water, so a dripping relief valve is noticed early.
- Clear drain line: a blocked line turns the tundish into a flood risk, so see how to unclog a drain for related problems.
- Safe termination: the pipe should end at a suitable drain or grate, as covered in our drain grates guide.
- Licensed work: tundish drain installation is part of a compliant hot water installation and belongs to a licensed plumber.
- Dripping relief valve: a small drip can mean high pressure, so check the PRV before blaming the relief valve.
- Annual checks: lift the relief valve lever briefly if the maker recommends it, and look for steady dripping afterwards.
Hot water system warranty period and your PRV
We do not quote warranty lengths here, because they differ by brand and model, and the paperwork that came with your unit is the only source that counts.
| What to check | Why it matters |
|---|---|
| Manufacturer’s warranty period | Each maker states their own term for the tank, parts and labour; it is on the paperwork |
| Installation conditions | Many warranties depend on correct installation, including pressure control where mains pressure is high |
| Licensed installer and paperwork | A Certificate of Compliance shows the work met the Plumbing Code of Australia |
| Brand details | Brands such as Rheem, Rinnai, Dux, Bosch and Stiebel Eltron publish their own conditions |
| Workmanship warranty | Separate from the product warranty; ask the plumber to state both in writing |
PRV and water hammer
Water hammer is the bang you hear when a tap or washing machine valve shuts quickly and the moving water slams to a stop. High pressure makes it worse.
- What a PRV does: it reduces the force behind the slam, but it will not always cure the bang on its own.
- Other causes: loose pipe clips, air in the line and fast-closing valves also play a part.
- Where to read more: our water hammer guide covers causes, arrestors and how a plumber decides between them.
- Timing clue: if the noise started after a new appliance or a PRV change, tell the plumber, because that often points to the cause.
PRV and low water pressure in the house
Low pressure is not a reason to fit a PRV. The valve only reduces pressure, so it cannot lift a weak supply.
- Blocked strainer: grit collects in the PRV strainer and restricts flow, which a plumber can clean in minutes.
- Partly closed stop tap: a valve left half shut after a plumbing job is a common and cheap cause.
- Setting too low: a PRV that has drifted or been set too low makes every shower weak, so check it first.
- Corroded pipework: old galvanised pipe narrows inside, and a PRV cannot fix that restriction.
- Where to read more: our low water pressure guide walks through the checks.
PRV FAQs
How to install a hot water system?
A licensed plumber isolates the water and power or gas, drains the old unit, checks the PRV, connects the new unit with isolation valves, fits the relief valve with a tundish drain and tests everything. Sydney Water says replacing a hot water system needs a licensed plumber, so book one and ask for a Certificate of Compliance.
What does a PRV do?
A PRV reduces the pressure of the mains water entering your home so taps, appliances and the hot water system are not overloaded. It holds a steady outlet pressure even when street pressure rises. It will not increase low pressure, and it does not control hot water temperature.
What is a 2 bar pressure reducing valve?
It is a PRV described by its outlet pressure setting, shown on the label. Check that the setting suits both your hot water unit’s data plate and the fixtures in the house. A licensed plumber should select the model, set it and note it on the quote.
Do I need TMV valves as well as a PRV?
They do different jobs. A PRV controls pressure; TMV valves limit hot water temperature at the outlet to reduce scald risk. The Plumbing Code of Australia sets where tempered water is needed, so ask your licensed plumber which outlets in your home need a TMV.
Does a PRV affect my hot water system warranty period?
It can. Many manufacturers tie the warranty to correct installation, which may include pressure control where mains pressure is high. Warranty lengths vary by brand, so read your unit’s paperwork, use a licensed plumber and keep the Certificate of Compliance with your records.
How much does a PRV cost to install in Sydney?
Plumber labour is $92–$230 per hour plus a call-out of $69–$170, and the valve adds a modest cost. A supplied and fitted PRV typically falls around $300–$900 (indicative — get itemised quotes). Booking in business hours and bundling with other jobs keeps the price down.
Getting a PRV installed in Sydney
If your pipes bang, your taps drip or your relief valve weeps, ask for a pressure test. TQN Plumber’s licensed Sydney plumbers measure your pressure, fit or adjust the PRV and give you a Certificate of Compliance. Check your options in our slimline water tanks guide or get a free quote.
