How to fix a leaky pipe joint

A leaky pipe joint can swell a cupboard, stain flooring or encourage mould within days. Joints commonly fail because a compression washer has hardened, a union nut has loosened, a thread is corroded or a push-fit seal has shifted. Trace the water to its source before dismantling anything, as a leak travelling along a pipe can be mistaken for a failed fitting.

Most household leaks can be isolated and repaired with basic tools, but the right method depends on whether the connection is threaded, compression-fit, push-fit or solvent-welded. Local conditions also matter: older Melbourne and Sydney homes may combine galvanised steel, copper and later plastic pipework, while Adelaide's hard water encourages scale. Work methodically and use a licensed tradesperson for concealed or extensive damage.

Trace the leak to the actual joint

Watch the joint while the tap or shower runs, then wipe it dry and look again. A drip from the nut, thread or connector body points to a different fault from water tracking along the pipe. Mould, staining or a ceiling bulge may mean the leak has been running behind a wall or above a concealed joint.

Check whether the flow changes when the fixture is closed. A steady leak with the tap off suggests a failed valve; a joint that leaks only under pressure usually indicates a damaged seal, loose fitting or split pipe. If the joint is on a riser or shared pipe, isolating one tap will not stop the flow, so find the nearest suitable isolation valve.

A dry paper towel makes a simple leak detector. An adjustable spanner, often called a shifting spanner in Australia, can check whether a compression nut has moved, but do not wrench against thin copper or plastic pipe because this can distort it and create another leak.

Isolate the water and prepare the area

Close the fixture's isolation valve first. If there is no accessible valve, use the main stopcock or the valve by the meter, then run a nearby cold tap to draw down the line and confirm that flow has stopped. Let a hot-water line cool before handling it, and protect the drain from very hot discharge.

Place a bucket, towels and absorbent material beneath the joint. If water could reach a power point, switch off the relevant circuit at the switchboard and keep electrical appliances away from the wet area. Sydney, Melbourne and Adelaide often impose water restrictions during dry periods, so relieve pressure with controlled flow rather than leaving a hose running.

Photograph the joint and nearby pipework before dismantling it. Older Australian homes often contain mixed pipe sizes and fittings from different renovations. Bunnings and Reece stock common metric fittings, while a plumbing merchant or trade counter may be needed for unusual BSP threads, galvanised connectors or a matching compression olive. Confirm actual diameter and thread form before buying.

Match the repair method to the fitting

A compression joint uses a nut, olive or ferrule and often a rubber washer. A slight weep may respond to tightening the nut by a fraction, but persistent drips usually need disassembly and a replacement washer. Put thread sealant on this type of joint only if the manufacturer specifies it; the washer or olive normally creates the seal.

Threaded joints need the correct fitting, not extra force. Clean the threads, inspect them for flattened or corroded sections and replace damaged parts. Apply PTFE tape only to a tapered pipe thread and follow the product instructions; a compression olive, parallel thread or push-fit fitting can be damaged by unnecessary tape. Hand-tighten first, then snug the fitting evenly.

Push-fit fittings open with the correct release tool, while PVC pressure pipes may be joined with matched primer and solvent cement. Cut pipe square, deburr the end and replace any distorted O-ring. A pipe repair sleeve with a rubber lining can stop a small leak temporarily, but it is unsuitable for hot water, high pressure or permanent use unless its rating specifically permits it.

Reseal or replace the leaking fitting

Before dismantling a compression joint, mark the olive's position and note which way the nut turns. Support the pipe so it cannot twist. Remove the old washer or olive, clean the thread and inspect each sealing surface. Fit the replacement and tighten gradually without crushing the washer.

For a threaded connection, confirm the diameter and thread form before buying a replacement. A nominally similar fitting can have a different thread or outside diameter. Wrap pipe thread in the direction recommended by the tape manufacturer, keep tape away from the thread end, and tighten the new fitting with a clean, correctly sized spanner.

When using solvent cement, dry both surfaces, apply compatible primer and cement, push the joint together fully and hold it for the time stated on the product. It may feel firm before reaching full cure, so do not pressurise it early. For push-fit repairs, lubricate a new O-ring with silicone lubricant, seat the pipe fully and confirm that the collet grips it evenly.

Test the repair and decide when help is needed

Open the isolation valve slowly and let the line regain pressure. Hold a dry tissue beneath the repaired joint, run the fixture for several minutes and check again. A joint that drips immediately needs another inspection; one that remains dry under normal pressure has a better chance of holding. Record the fitting type, size and parts replaced.

If the joint still leaks after fitting a new washer or component, the pipe may be cracked, corroded or incorrectly prepared. Repeated tightening can strip a nut or split a ferrule. Raised timber-floor houses are common around Brisbane, and damp subfloor conditions can encourage termites and timber decay, so isolate the water and arrange an inspection rather than leaving the area wet.

Use a licensed plumber for concealed pipework or changes to a shared riser, especially where building or insurance requirements apply. Australian requirements are state-based: NSW uses WaterMark for technical oversight of plumbing licensing, while the Victorian Building Authority licenses practitioners and administers Victoria's plumbing regulations. For a larger incident, obtain advice from a licensed plumber experienced in water damage repair services so the pipe, drying work and possible rebuilding are considered together.

Prevent repeat leaks and document the repair

Once the repair holds, inspect nearby joints, isolation valves and pipe supports for corrosion, stains or contact with a sharp edge. In Adelaide, hard-water scale can make a fitting look rough or stiff even when it has not failed, so clean it gently and replace it if the sealing surface is pitted or uneven.

Keep the main stopcock accessible and learn where the valves sit under sinks, basins and outdoor hose taps. A fixed inspection routine can catch a slow drip before it damages joinery. The site's broader home maintenance guidance can support a household schedule for checking visible plumbing and documenting moisture around cabinets.

Save the receipt, spare washers and the photograph taken before the repair. If an insurer is involved, check the policy's excess and evidence requirements before remediation starts. A clear record of the failed part, repair method and affected area can make later work easier to assess.

A sound repair should stay dry during normal use and leave no dampness around the cabinet or floor. Persistent moisture after a repair indicates that the joint or an adjacent part still needs attention.

The final practical check is to place a dry paper towel beneath the repaired joint and inspect it again after fifteen minutes.