Plumbing glossary: M

Got an appointment with a plumber? Use our plumbing glossary to hold the conversation.

M tubing – an industry standard for copper tubing defined by the tube wall thickness and identified by a red stripe

MC Tank – acetylene tank holding 10 cu.ft. of gas, once used to fuel motorcycles and now used for plumbing

MCLMaximum Contaminant Level – the maximum level of a contaminant allowed in water by law, which is based on potential health risks and what treatment is readily available

MHTMale Hose Threads – the threads on the outside of a connection

MIPCMale Iron Pipe Connection – standard external threads on pipe and fittings

MPNMost Probable Number – term used to indicate the number of organisms that, according to statistical theory, would be most likely to produce the results observed in certain bacteriological tests – usually expressed as a number in 100 ml of water

Macerator – a device installed in a drain line between a toilet and the soil stack to reduce solids to liquid form

Magnesium – an element in the Earth’s crust that makes water hard when dissolved, causing scale and insoluble soap curds

Main – the primary artery of water supply in a drain system

Male fitting – fitting that is inserted into another fitting

Malleable fittings – fittings made of cast iron, a metal which is soft and pliable

Manganese – an element sometimes found dissolved in ground water that causes black stains

Manhole – access opening to a hole, usually with a cover, through which a person may enter a sewer, boiler, drain, etc. – it’s usually round to prevent the cover from falling into the opening

Mapp gas – a colourless, flammable gas made by combining liquefied petroleum gas with Methylacetylene-Propadiene – it is a stable, non-toxic fuel used for brazing and soldering

Meter tailpiece – an adapter connecting a water meter to the water supply line

Mission coupling – a neoprene flex coupling, connecting PVC to PVC, or clay to PVC

Mixing valve – mixes hot and cold water to achieve a specified delivery temperature

Monobloc faucet – a single-handle faucet, usually a lever

Multi-port valve – rotary type backwash valve, which can replace up to six regular gate valves

Multi-stage pump – a pump that has more than one impeller

Municipal water – water supplied by a city for public use

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