16 Oct How to Find a Pipe Leak Underground in an Inner West Terrace: Is It Your Water Line, Your Drain, or Your Neighbour’s?

The pavers by the back step have dropped about a centimetre since winter. There’s a damp strip along the side passage that never quite dries out, and on still evenings the courtyard carries a faint smell you’d rather not name. So you did what every guide told you to do. You turned off every tap, read the water meter, waited an hour and read it again. The numbers didn’t budge. Good news, surely? Not necessarily. That test tells you about one pipe only, and a terrace built more than a century ago usually has at least three running beneath it, some of them older than anyone living on your street.

Here’s what trips most people up. The water coming into your home travels under pressure, so a crack in that line pushes water through the meter whether anyone’s using it or not. Your sewer and stormwater pipes work differently. They rely on gravity, sit mostly empty and only leak when something’s flowing through them, like a shower, a flush or a decent downpour. Leaking pipes of that sort can soak the ground under your floor for years without adding a cent to your water bill. And in older terrace rows there’s a third possibility that rarely crosses anyone’s mind: the pipe doing the damage might not be yours alone. Which one you’re dealing with changes who you call, what it costs and, sometimes, who pays. Here’s how to narrow it down before you start digging up the courtyard.

Water Line, Drain or Next Door? How to Find Pipe Leak Underground the Smart Way

Start with the supply line, because it’s the easiest to rule in or out. Shut off everything that uses water, including the dishwasher, washing machine and garden irrigation, then watch the small red dial or triangle on your meter. If it creeps with the house silent, the leak is on the pressurised side. It’s tempting at this point to order a cheap water leak detector for underground pipes online, but hobby-grade gadgets tend to struggle through the compacted fill, broken brick and old sandstock rubble that sits under most terrace backyards. They’ll often confirm what the meter already told you without narrowing down where.

If the meter stays still, don’t relax just yet. Drain leaks give themselves away through timing. Run a full load of washing or a long shower, then check the damp patch twenty minutes later. If it’s noticeably wetter, suspect the sewer. Does it spread after a storm but vanish during a dry week? That points to stormwater. Other clues are a strip of grass greener than the rest, pavers sinking along one line, rats hanging around the side passage and blockages that keep coming back no matter how often they’re cleared. Century-old terracotta was laid in short sections with mortar joints, and once those joints crack, tree roots and shifting clay finish the job.

Then there’s the neighbour question. Plenty of older terrace rows were connected to a single shared sewer line that snakes beneath several backyards before it reaches the main, and every owner connected to it shares responsibility for it. Ask your water authority or a plumber for the property’s sewer service diagram, keeping in mind the old ones aren’t always accurate, and have a friendly chat over the fence before any work is booked. It’s far easier to split a repair bill when everyone’s seen the problem.

This is where professional underground pipe leak detection earns its keep, because each pipe needs a different tool. A proper water leak detector for underground pipes uses acoustic sensors or tracer gas to pinpoint pressurised leaks, while drains are checked with a CCTV camera fed through an existing access point, sometimes backed up by dye or smoke testing. Once the fault is on screen, pipe leak repair can often be done from the inside by relining the damaged section, which matters a great deal when your only access is a narrow side passage and the pipe runs under a kitchen extension.

Stop Guessing and Start With the Camera

The short version? Don’t let a clean meter reading talk you out of investigating, and don’t let anyone start digging until they know which pipe they’re chasing. Leaking pipes under an old terrace rarely fix themselves, and the longer water washes soil from under your footings, the bigger the eventual bill. You’ll find more practical advice on caring for older homes at piperelininginnerwest.com.au.

Revolution Pipe Relining has relined more than 31,000 metres of pipe, and every relined section is backed by a lifetime guarantee plus a free annual CCTV check to keep an eye on it. It’s a family-run business, so there’s a good chance one of the owners will be on the tools at your place. Our team starts with thorough underground pipe leak detection, hands you the footage, and only recommends pipe leak repair when the camera proves you need it. If you’re still unsure how to find pipe leak underground in Inner West homes like yours, call 1300 844 353 for a free estimate.