Pipe: Types, Costs & Buying Guide (2026)

By Mohammad Barzegar, Director, TQN Plumber · Reviewed by a licensed NSW plumber · Updated October 2026 · 12 min read

A pipe is a rigid or flexible tube that carries water, waste, gas or air through a building, and the right material depends on what it carries and where it runs. In Australian homes, water supply lines are usually copper or PEX, while drains and sewers are mostly PVC.

This guide suits homeowners planning a renovation, repair or new build. It covers the main types, how sizes are named, what drives cost, which fittings and sealants go with each material, and which jobs need a licensed plumber.

Key points

Copper and PEX are the usual choices for drinking water lines, while PVC handles most household drainage, sewer and stormwater work.
Sizes are named by nominal size (such as DN15) rather than exact diameter, so always match fittings to the product data sheet.
Galvanised steel in older Sydney homes corrodes from the inside, which is a common cause of low pressure and rusty water.
Repairing leaks in private water lines needs a licensed plumber, who should give you a Certificate of Compliance when the job is done.

What is a pipe?

In plumbing, a pipe is a pressure-rated or drainage-rated tube joined with fittings to form a sealed system. Pressure lines carry mains water to taps and appliances; drainage lines carry waste away by gravity.

Every length you buy is printed with markings that tell a plumber what it is approved for. Reading those markings is the quickest way to avoid buying the wrong product.

Material: copper, PEX, PVC, polyethylene, steel, cast iron or vitreous clay, each with its own jointing method and lifespan.
Nominal size (DN): a naming size such as DN15, which is close to but not the same as the measured diameter.
Wall thickness or class: sets how much pressure the line can handle and whether it suits burial or exposure.
Pressure or drainage rating: printed on the product; drainage-grade PVC must never be used for pressurised water supply.
Jointing method: soldered, press-fit, crimped, solvent-welded, rubber-ring, threaded or push-fit, which must match the fittings.
Certification: look for WaterMark certification and reference to AS/NZS 3500 before anything goes into a drinking water system.

Types of pipe for Australian homes

Type	Best for	Strength and lifespan	Price band
Copper	Hot and cold water supply, gas (with the correct type)	Strong, heat-resistant, very long-lasting in most water conditions	$$$
PEX (cross-linked polyethylene)	Hot and cold water supply, renovations, retrofits	Flexible, freeze-tolerant, long-lasting when installed to the maker’s guide	$$
PVC (uPVC)	Sewer, waste, vent and stormwater drainage	Rigid and durable; brittle in prolonged sun if unpainted	$
Polyethylene (poly)	Underground water services, irrigation, rural lines	Flexible and tough, but needs protection from sharp backfill	$
Multilayer (PE-AL-PE)	Water supply where a line must hold its shape	Bendable yet stable; relies on matched fittings	$$
Galvanised steel	Found in older homes; rarely used for new water lines	Strong but corrodes internally over decades	$$
Stainless steel	Commercial, coastal and high-hygiene installations	Very corrosion-resistant and strong	$$$
Cast iron and vitreous clay	Older sewers and stacks in established suburbs	Long-lived, but joints let in tree roots and iron can rust through	Replacement work, $$–$$$

PEX

PEX is the flexible plastic tube most plumbers now run through walls in renovations. It bends around corners with fewer joints. Read our PEX pipe guide for fittings and installation rules.

Copper

Copper remains the benchmark for hot water and exposed runs because it handles heat and looks tidy. Our copper pipe sizes and fittings guide explains tube types and joints.

PVC

PVC carries almost all household waste and stormwater. House sewer drains are often described by the 4 inch size (indicative — your drainage plan sets the actual size); see the 4 inch PVC pipe guide for grades and uses.

Steel

Galvanised and stainless steel show up in older houses and commercial jobs. Our steel pipe sizes guide covers sizing, threads and replacement options.

Pipe cost in Australia

Item	Materials	Installed by a plumber
PVC drainage lengths and fittings	$ (cheapest per metre)	Labour and excavation usually cost more than the material
Polyethylene water service	$	Trenching and connection drive the price
PEX water supply	$$ (fittings add up quickly)	Faster to run than copper, which can trim labour
Copper water supply	$$$	Skilled jointing; neat for exposed runs
Stainless steel	$$$	Specialist fittings and tools
Plumber labour (Sydney, Oct 2026, incl. GST)	—	Call-out $69–$170 plus $92–$230 per hour, typically $140 for each
After-hours burst repair (Sydney, Oct 2026)	—	Visit $290–$805, typically $520

Access: lines under slabs, behind tiled walls or in tight subfloors take far longer to reach than an open garden trench.
Material choice: copper and stainless cost more to buy, while PEX fittings can make a cheap tube surprisingly expensive.
Run length and joints: every bend, tee and valve adds a fitting and labour time, so a simple layout keeps the bill down.
Existing condition: corroded galvanised lines often crumble when cut, turning a small repair into replacing a whole section.
Making good: patching plasterboard, retiling or reinstating concrete is usually separate from the plumbing quote.
Timing: after-hours labour in Sydney runs $170–$345 per hour, so isolate a leak and book business hours when you can.

Pros and cons of each pipe material

Pros

Copper handles high temperatures, resists UV and has a long track record in Australian hot water systems.
PEX bends around obstacles, needs fewer joints and is quicker to install in an occupied house.
PVC is light, cheap and easy to cut and solvent-weld, which suits long drainage runs.
Polyethylene comes in long coils, so buried services can run with very few joints in the ground.
Stainless steel resists corrosion in coastal air and stands up to physical knocks in exposed locations.

Cons

Copper costs more, needs skilled jointing and can be targeted by thieves on building sites.
PEX degrades in sunlight, so it must be covered, and it only works with matched fittings.
PVC can become brittle in prolonged sun and is noisier than cast iron when waste flows through walls.
Polyethylene can be pierced by rocks in backfill and is easy to damage with a shovel.
Galvanised steel rusts internally, narrowing the bore and causing discoloured water and weak flow.

How to choose the right pipe

Identify what it carries: drinking water, hot water, waste, stormwater or gas each need a material rated for that use.
Check where it runs: buried, in walls, under slabs or exposed to sun, because UV and backfill rule out some materials.
Match the existing system: joining new to old needs compatible transition fittings to avoid leaks and dissimilar-metal corrosion.
Confirm the size on the data sheet: nominal sizes differ between materials, so never assume two DN15 products fit together.
Look for WaterMark certification on anything carrying drinking water, and keep the product labels for your records.
Weigh lifetime cost, not just purchase price: cheap tube with expensive fittings or a short service life rarely saves money.
Ask a licensed plumber which material suits your house, because they’re responsible for compliance with AS/NZS 3500.

Pipe installation and maintenance essentials

Use a licensed plumber for water and drainage work: Sydney Water lists repairing leaks in private water lines and clearing private wastewater blockages as licensed work.
Get a Certificate of Compliance when the job is finished; it confirms the work meets the Plumbing Code of Australia.
Follow the manufacturer’s spacing for clips and supports; sagging runs strain joints and cause water hammer and noise.
Keep drainage falls continuous, as specified on the plans, so waste doesn’t settle and block the line.
Insulate exposed hot and cold lines with pipe insulation wrap to cut heat loss and reduce condensation in roof spaces.
Protect plastic tube from sunlight with paint, lagging or conduit, as listed in the product instructions.
Book a camera inspection if drains block repeatedly; a pipe cam shows roots, cracks and sags, as explained in our CCTV drain inspection guide.

Pipe sizes: DN, millimetres and inches

Australian sizes mix metric nominal sizes with older imperial names. Treat these as starting points and confirm against the product data sheet.

DN15 pipe size is a common nominal size for household taps and branch lines, often matched to ½-inch fittings (indicative — check the data sheet).
22mm to imperial: 22mm copper tube is commonly paired with ¾-inch fittings, but sizing systems vary (indicative — confirm with your supplier).
4 inch PVC pipe is the size most often named for house sewer drains (indicative — your drainage plan sets the actual size).
125mm pipe is a larger size mostly used for stormwater and commercial drainage rather than household supply (indicative — check the hydraulic plan).
Steel water pipe is sized by nominal bore and thread type, which differ from copper and plastic sizing.
Measure the outside diameter with callipers and take an offcut to the supplier, rather than guessing from the nominal size.

Pipe fittings, connectors and joiners

Fittings change direction, size or material, and they must match the line’s jointing system. Mixing brands or systems is a common cause of slow leaks.

PVC plumbing fittings such as elbows, tees, junctions and reducers are solvent-welded; see our PVC pipe fittings guide.
PVC pipe connectors and joiners need primer and solvent cement rated for the job; our PVC pipe glue guide explains the difference.
A pipe socket is the enlarged end of a length or fitting that receives the next section, sealed by solvent or a rubber ring.
Threaded PVC pipe suits low-pressure jobs and adaptors; thread sealing matters more than tightening force.
Push-fit water pipe fittings join tube without heat; read about John Guest push-fit fittings before using them.
Flare fittings on soft copper need a cleanly formed flare; our flaring block guide shows the tool, though gas work stays with a licensed gasfitter.

Sealing pipe threads, gaskets and joints

The right sealant depends on the joint, the pressure and whether the water is for drinking. The wrong product can fail quietly inside a wall.

Thread tape wraps male threads in the tightening direction; our plumber’s tape guide shows how many wraps and which grade.
Paste or liquid thread sealant suits larger or rougher threads; compare options in our thread sealant guide.
Rubber gaskets and rings seal flanges, unions and rubber-ring drainage joints; see our rubber gaskets guide for materials.
An RTV gasket is silicone that cures in place to form a seal; check it’s approved for drinking water before using it on supply lines.
Clear silicone seals around fixtures and penetrations, not pressurised joints; our clear silicone sealant guide covers where it belongs.
Never use sealant to fix a leaking joint under pressure; the joint needs remaking, which is licensed work on water lines.

Hoses, valves, clips and other pipe accessories

Several products sit around the main lines and are searched for alongside them. Some are DIY items; others are trade-only.

Hose and fittings for the garden screw onto an outdoor tap; secure barbed connections with clamps from our hose clamps guide.
Greywater hose carries laundry or bath water to the garden; it must be clearly marked and kept separate from drinking water.
RMC valves include tempering, pressure-limiting and isolating valves used on hot water systems, all fitted by a licensed plumber.
A butterfly valve with pneumatic actuator is a quarter-turn valve opened by compressed air, used in commercial and industrial lines, not homes.
Galvanised pipe clips fix steel lines; for copper, use lined or compatible clips so dissimilar metals don’t corrode.
Plumbing conduit is a protective sleeve through slabs and walls; electrical conduit is a different product and isn’t for water.

Pipe FAQs

What does hard water mean?

Hard water contains high levels of dissolved minerals, mainly calcium and magnesium. It leaves white scale on taps, showerheads and inside hot water units, which reduces flow and efficiency over time. Your water supplier can tell you how hard your local water is, and bore or tank water often differs from mains supply.

What is a duo valve?

A duo valve usually combines an isolating valve and a non-return valve in one body. It’s commonly fitted on the cold water inlet of a hot water system so the unit can be shut off and hot water can’t flow back into the cold line. Installation is licensed work.

What is the best water pipe for a house?

Copper and PEX are the most common choices for household water supply. Copper suits exposed runs and areas near hot water units, while PEX is faster to install in walls during renovations. A licensed plumber will choose a WaterMark-certified product that suits your water conditions and layout.

Can I replace a water pipe myself?

No. Sydney Water lists repairing leaks in private water lines as work for a licensed plumber, and the same applies to replacing them. You can fit garden hoses and hose fittings to an outdoor tap, but anything connected to the water service itself needs a licensed plumber.

What size is DN15 pipe?

DN15 is a nominal size, not an exact measurement, and it’s widely used for household taps and branch lines. The actual outside diameter depends on the material, so a DN15 copper line and a DN15 PEX line may need different fittings. Always check the product data sheet.

Why is my old steel water pipe causing low pressure?

Galvanised steel corrodes from the inside, and the rust narrows the bore until less water gets through. You might also notice brown water after the taps have been off. Repairs often fail on corroded lines, so a plumber may recommend replacing the affected section with copper or PEX.

Getting pipe installed in Sydney

If your house still has galvanised lines, a leak you can’t find or drains that keep blocking, the next step is a licensed inspection. TQN Plumber’s Sydney plumbers repair and replace water and drainage lines, supply WaterMark-certified materials and issue a Certificate of Compliance. Get a free quote before you start your renovation.