Plumbing terms, explained in plain English
The words your plumber uses, what they mean, why they matter, and when they affect your home. Written by the licensed team at Ready Plumbing.
What Is Backflow Prevention?
Backflow prevention stops water flowing backwards through your plumbing into the drinking water supply. Backflow devices, ranging from simple check valves to testable assemblies, protect the mains from contamination when pressure drops or reverses, and are required wherever a property's water could pose a hazard to the supply.
What Is a Boundary Trap?
A boundary trap is a fitting on your sewer line near the property boundary, usually visible as a white cap or cast-iron lid at the front, side or back of your property. It's a water-seal trap that stops sewer gases from the street mains entering your property's pipes, and it's a key inspection and clearing point when drains block.
What Is a Ceramic Disc Tap?
A ceramic disc tap is a quarter- or half-turn tap with an inbuilt valve made of two polished ceramic discs. Rotating the handle aligns openings in the discs to let water flow. They contain no washers: when one leaks, the ceramic cartridge is replaced rather than a washer.
What Is a Flow Switch?
A flow switch is the sensor inside an instantaneous (continuous flow) hot water unit that detects water flowing through the heater and tells it to ignite. If flow drops below the switch's threshold (often due to partially blocked inlet filters), the unit shuts off, which is why these heaters are notorious for stopping and starting.
What Is Hydro Jetting?
Hydro jetting (also called water jetting) clears blocked drains using high-pressure water driven through a specialised nozzle, powerful enough to cut tree roots back to the pipe wall and strip grease, while scouring the full bore of the pipe clean rather than just punching a hole through the blockage.
What Is a Jumper Valve?
A jumper valve is the internal valve in a traditional Australian tap that carries the tap washer, the rubber seal that stops water flow when you turn the tap off. When a jumper-valve tap drips, a worn washer (or worn valve seat beneath it) is almost always the cause.
What Is an Overflow Relief Gully?
An overflow relief gully (ORG) is a grated drain fitting outside your home, connected to your sewer line, designed to release sewage outside if the line blocks, instead of letting it overflow inside your home through toilets and floor wastes. Sewage discharging from the gully means your sewer is blocked.
What Is Pipe Relining?
Pipe relining is a no-dig method of repairing damaged underground pipes: a resin-saturated liner is inserted through the existing pipe and cured in place, forming a smooth structural new pipe inside the old one. It permanently seals cracks, breaks and tree-root entry points without excavation.
What Is a Pressure Limiting Valve?
A pressure limiting valve (PLV) reduces incoming mains water pressure to a safe, consistent level for your home's plumbing, commonly 500 kPa. It protects pipes, tapware, appliance hoses and hot water systems from the damage caused by excessive street pressure.
What Is a Sacrificial Anode?
A sacrificial anode is a magnesium rod inside a steel hot water tank that corrodes deliberately so the tank doesn't. The electrolysis in the water eats the anode instead of the steel, and once the anode is consumed (typically around 5 years), the tank itself starts corroding.
What Is a Tempering Valve?
A tempering valve blends hot water from your hot water system with cold water so the water delivered to your bathroom taps can't exceed a safe temperature (50°C for most homes). It's a required part of a compliant hot water installation in NSW.
What Is a Thermocouple?
A thermocouple is a small safety sensor that sits in a gas appliance's pilot flame. While it senses heat it holds the gas valve open; if the pilot goes out, it shuts off the gas so unburnt gas can't leak. When a thermocouple fails, the pilot light won't stay lit: the classic 'no hot water' fault on gas storage systems.
What Is Water Hammer?
Water hammer is the banging or thudding sound from pipes when water flow stops suddenly, a pressure shockwave created when fast-moving water hits a closed valve. Common triggers are washing machines, dishwashers and quickly closed taps; over time the repeated shock loosens fittings and can cause leaks.
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