Glossary
Plumbing terms in plain English.
Quotes, articles or your plumber tossing around acronyms? Here's what they actually mean, from QBCC and PVD to AWTS and AS3500.
- AS3500
- The Australian Standard for plumbing and drainage. Every plumbing install in Australia must comply with it. Covers water services, sanitary plumbing and drainage, stormwater drainage, and heated water services.
- AWTS
- Aerated Wastewater Treatment System. An on-site sewage treatment plant used where mains sewer isn't available. Common on Gold Coast acreage. Sewage is aerated, treated, and the treated effluent is disposed of via a sub-surface irrigation field.
- Backflow prevention
- Devices that prevent contaminated water from siphoning back into the drinking water supply. Required on properties with potential cross-connection risk (irrigation, fire services, commercial). Annual testing required by council.
- Bib tap (hose cock)
- An outdoor tap with a hose thread, garden tap, washing-machine tap, outdoor laundry tap. Generally brass with a chrome finish; replaced often on coastal homes due to salt corrosion.
- Capping a service
- Plumbing-speak for permanently terminating a water, gas or drainage line. Done when removing an appliance or decommissioning a fixture. Gas capping requires a licensed gas fitter and a compliance certificate.
- CCTV inspection
- Sending a camera down a drain or sewer line to inspect from the inside. Used for diagnosing blockages, locating leaks, and proving the cause of issues before quoting repairs. Hills uses CCTV before any major drain work.
- Compliance certificate
- Legal document certifying that plumbing or gas work was done to code by a licensed practitioner. Mandatory for all gas work in QLD. Required for property sale and insurance claims.
- Continuous flow (hot water)
- Tankless hot water system that heats water on demand as it flows through, no storage tank. Compact, good for tight spots, handles peak demand. Rinnai Infinity is the best-known brand.
- Copper pipe
- Traditional Australian water pipe material. 30-50 year typical lifespan. Develops pinhole leaks from the inside as it ages. Largely replaced in new builds by PEX, but still common in homes built before 2000.
- DKIM
- DomainKeys Identified Mail, an email authentication standard. Not plumbing, but relevant if you're setting up email-based form submission on a plumber's website (which is what we did).
- Drain eel
- Mechanical drain-cleaning tool with a spinning cutting head. Shears off the visible blockage but doesn't scour the pipe wall, so root mats and grease tend to grow back. Cheaper than jetting, less effective.
- Fall (in drainage)
- The gradient of a drain run. Australian Standard for sanitary drainage is 1:60 minimum (about 17mm drop per metre). Insufficient fall = water sits in the pipe = blockages. Too much fall = water races ahead leaving solids behind.
- Fit-off
- Final stage of plumbing work on a renovation or new build, installing tapware, mixers, basins, toilets and other visible fittings after the walls/tiles are done. Where the visible quality of the job is decided.
- Flex hose (braided)
- Flexible braided water hose connecting a fixture (toilet, basin tap, washing machine, dishwasher) to the wall valve. 5-10 year lifespan. When they fail, they fail catastrophically. Replace at 7 years.
- Form 4 (QBCC)
- The plumbing compliance form issued at the end of a new build or major renovation, certifying the plumbing work complies with AS3500. Required for the certificate of classification.
- Heat pump (hot water)
- A hot water system that extracts heat from outdoor air to heat water, about 3-4x more efficient than a standard electric storage system. Federal STCs + state rebates make these very attractive in 2026.
- Honeycomb (sewer)
- Slang for the visible cellular structure of a long-failing clay sewer pipe, the inside surface becomes pitted and rough, slowing flow and catching debris. Usually a precursor to collapse.
- Hot water TPR valve
- Temperature and Pressure Relief valve fitted on every hot water tank. Releases water if temperature or pressure exceeds safe limits. Should drip occasionally during a hot day, continuous drip means it's faulty or there's a pressure problem.
- Hydrostatic test
- Pressure-testing a water service by filling it with water and pressurising it above normal mains pressure. Confirms no leaks before walls/floors are closed up. Standard step at the end of new build rough-in.
- Inspection opening (IO)
- A capped access point on a drainage line for inserting cameras or eels. Required at intervals along sewer runs. Their location is shown on as-built drainage plans.
- Jetting (high-pressure)
- Drain-cleaning method using high-pressure water (typically 4,000-5,000 PSI for residential) with specialised nozzles. Scours the pipe wall properly, clears root mats, grease and buildup. Far more effective than mechanical eeling.
- LPG
- Liquefied Petroleum Gas, bottle gas. Used where mains natural gas isn't available, common on Gold Coast acreage. Stored in 45kg or 90kg bottles outside the home, regulated to working pressure, then piped to appliances.
- Mains pressure
- The water pressure delivered to your property from the council water main. On the Gold Coast typically 400-700 kPa. Above 500 kPa, a pressure-limiting valve is required by AS3500 to protect your fittings.
- Mixer (single-lever tap)
- Modern tap with one handle that controls both flow and temperature. Inside is a ceramic disc cartridge, replaceable when worn. Lifespan 5-15 years on the cartridge; tap body lasts decades if quality.
- PEX (cross-linked polyethylene)
- Modern flexible plastic water pipe. Replacing copper in most new builds, easier to install, no corrosion, longer expected life. Two standards: PEX-A (most flexible, premium) and PEX-B (cheaper, still good).
- Pressure-limiting valve (PLV)
- A valve installed at the water meter that reduces incoming mains pressure to a safe level (typically 500 kPa). Mandatory on new builds in QLD. Without one, high-pressure events damage tapware, flex hoses and mixer cartridges.
- PVD (Physical Vapour Deposition)
- Premium tapware finish technology. The colour (brass, matte black, gunmetal) is deposited at the molecular level, won't chip, scratch or wear off like cheap electroplated finishes. Essential for tapware in coastal areas.
- QBCC
- Queensland Building and Construction Commission, the regulator that licenses plumbers and gas fitters in QLD. Every plumber working on your house should be QBCC-licensed for plumbing; every gas fitter QBCC-licensed for gas.
- Rainwater harvesting
- Collecting roof rainwater into tanks for use on the property. Universal on Gold Coast acreage (where mains water doesn't reach). Tanks need overflow management, pump systems for pressurised supply, and inlet screens.
- Relining
- No-dig pipe repair technique. A resin-impregnated liner is inserted into the existing damaged pipe, then cured in place to form a new joint-free pipe inside the old one. 50-year design life. Used to fix cracked sewer pipes without excavation.
- Rough-in
- First stage of plumbing on a new build or renovation, installing all the pipes inside walls, under slabs and in ceilings before the walls are closed up. Where most of the labour is. Pressure-tested before walls go up.
- RPZ (Reduced Pressure Zone) device
- High-grade backflow prevention device for medium-to-high hazard situations. Required on properties with significant cross-connection risk (commercial kitchens, dental practices, etc). Tested annually.
- Sacrificial anode
- Magnesium or aluminium rod inside a hot water tank that corrodes preferentially to protect the steel tank from rust. Lasts roughly 5 years. Replacing it doubles the tank's expected life. Most homeowners never do this.
- Septic system
- On-site sewage disposal, a tank where solids settle and liquids drain to a soak field. Common on Gold Coast acreage where mains sewer isn't available. Different to AWTS (which actively treats the wastewater).
- Stormwater
- Rainwater runoff from roofs and paved areas. Drains separately from sewage to council stormwater mains (eventually discharging to creeks and waterways). Must not be cross-connected to sanitary sewer.
- TMV (Tempering Mixing Valve)
- A valve that mixes hot and cold water to a safe outlet temperature (typically 50°C for kitchen taps, 45°C for shower outlets). Required on hot water systems set above safe-touch temperatures. Prevents scalding.
- Variations
- Changes to the original quoted scope of work, quoted separately as they arise. Reputable plumbers only charge variations when the actual scope changes (e.g. hidden damage discovered). Beware quotes that come with surprise variations after work starts.
- WaterMark
- Australian certification for plumbing products. WaterMark-certified products are legal to install in Australian plumbing systems. Online tapware without WaterMark is technically illegal to install, and warranties are void.
- WELS (Water Efficiency Labelling Scheme)
- Australian water-efficiency rating system for taps, showers, toilets, washing machines and dishwashers. 0-6 star rating. Higher stars = lower water usage. 5+ stars is the current minimum for new installs.
- Workmanship guarantee
- A written guarantee from the plumber that the work they performed is fit for purpose. If it fails because of how it was installed (not the parts themselves), they'll come back and fix it. Standard on all Hills jobs.
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