Working pressure above the machine's maximum with a generous burst margin, and a temperature rating above the machine's hottest output.

Hose is rated for continuous working pressure, with a burst pressure that is a multiple of it. Using a hose whose working rating is below the machine's output is the single most dangerous shortcut in this equipment class.

Temperature is the rating people forget. A hose specified for a cold machine will soften and fail on a hot one, and the failure releases scalding water. Hot water machines need hose rated for their maximum outlet temperature.

Both ratings fall as the hose ages, abrades and takes damage, which is why the margin is not padding.

Match the rating to the machine, not to the job in hand - the machine may be turned up next week by someone who never saw the hose specification.

Longer hose loses pressure through friction, and the loss is greater on small-bore hose at high flow.

Every metre costs a little pressure. Over short runs it is negligible; over very long runs it becomes noticeable, and on a marginal machine it can be the difference between cleaning and not.

Bore size is the mitigation. A larger internal diameter loses much less over the same distance, which is why long runs on high-flow machines use larger-bore hose despite the extra weight and cost.

Joining several short hoses adds a coupling loss at each junction and creates more potential leak points. One continuous hose of the right length is better.

Against that, length is what stops the machine being moved. Moving a machine costs more time than a small pressure loss costs cleaning speed, so most operators run longer hose than strictly optimal - and that is usually the right trade.

Kinking at the gun end, abrasion from being dragged, crushing by vehicles, and age - in roughly that order.

The commonest failure is at the gun connection, where the hose is flexed back and forth thousands of times. Anti-kink springs at both ends address exactly this and are worth insisting on.

Abrasion wears the outer cover, then the reinforcement, and once wire is exposed the hose is condemned - visible wire is not a repairable condition.

Crushing by a vehicle damages the reinforcement invisibly. A hose that has been run over should be treated with suspicion even if it looks intact.

Ultraviolet exposure and heat cycling age the cover over years. Hoses stored in sunlight fail sooner than those on a reel in a shed.

Inspect for cover damage, exposed wire, bulges, stiffness and leaks at the fittings - and replace rather than repair. Repaired high-pressure hose is not worth the risk.

Screwed threads and quick-release couplings, in several standards - and mixing them is the usual source of frustration.

Threaded connections are the traditional arrangement at the machine and the gun, in different thread forms depending on the manufacturer and region.

Quick-release couplings allow tool changes without spanners and dominate professional use, but the coupling profiles are not universal. Two couplings that look identical may not seal or may not lock.

The practical approach is to standardise the whole site or fleet on one coupling system, with adaptors held for the exceptions. Mixed fleets waste time and lose adaptors.

Couplings are pressure-rated in their own right and must match the hose and machine.

O-rings and seals inside couplings are consumables. A coupling that weeps is usually a seal rather than a fault, and a small seal kit prevents a lot of downtime.

Manual for occasional use and long hose, spring-retracting for frequent short use, powered for very long or heavy hose.

A manual reel is simple, reliable and handles any hose length. It requires someone to wind it, which is why hoses on manual reels often end up on the floor instead.

Spring-retracting reels pull the hose back automatically and are ideal where the hose is deployed and recovered many times a day - a wash bay, a workshop, a kitchen. They have a length limit and a latch mechanism that needs occasional attention.

Powered reels handle long, large-bore, heavy hose - jetting reels in particular, where recovering a soiled hose by hand is slow and unpleasant.

Mounting matters as much as the reel. Wall, ceiling and post mountings each suit different layouts, and a swivelling bracket lets one reel serve a wider area.

Confirm the reel is rated for the pressure and temperature of the system, not just the hose it carries.

Drain them before freezing weather, keep them out of sunlight, and coil them without tight bends.

Water left in a hose freezes and expands, which damages the inner tube. On hot water systems the consequences of a compromised inner tube are serious.

Ultraviolet light degrades the outer cover over time. Storing hose on a reel indoors or under cover measurably extends its life.

Tight coiling forces bends below the hose's minimum bend radius and breaks reinforcement wires from the inside. Coil in large loops or use a reel.

Hanging a hose over a sharp edge or a nail concentrates the bend at one point and does the same damage.

Chemical residue left inside can attack the tube depending on the product, so flushing with clean water after chemical use protects the hose as well as the injector.

Yes - non-marking, food-grade, abrasion-resistant and hot-water hoses all exist for specific problems.

Non-marking hose has a light-coloured cover that does not leave black scuff marks on tiles, epoxy floors and painted surfaces. In showrooms, food plants and hospitals this matters.

Food-industry hose uses cover materials chosen for cleanability and compatibility with the environment, often in a distinctive colour so it is not used elsewhere.

Heavy abrasion-resistant covers suit construction, quarrying and anywhere hose is dragged over rubble constantly.

Hot-water hose carries a higher temperature rating and different cover compounds, and should be reserved for hot machines rather than used generally.

Jetting hose is a different product again - small bore, very flexible, with a smooth cover so it slides along a pipe rather than gripping it.

Colour coding hose by duty is a simple way to stop the wrong one being fitted.