The call
In July 2026 we were booked to a new build in Carine with both showers blocked. The job sheet just said “likely rubble”, which is what we expect in a home that has only just been handed over. Tilers, renderers and plasterers all wash their tools somewhere, and the nearest drain is usually a shower waste.
Most of our Carine work is tree roots in older sewer lines, so a house with no roots and no old pipe was a change. The fix still started the same way: test each drain, then put a camera down it before deciding what to do.
Two showers, two different blockages
The second shower was the easy one. Builder’s sand and grit had settled in the waste, and an air snake (a drain tool that fires a short burst of compressed air down the line) pushed it through and the shower cleared.
The ensuite shower did not budge. Our tech’s first thought was grout, and the camera proved it. About 62 centimetres down the pipe sat a pale lump of set concrete and grout, filling most of the bore, with water pooled behind it.
Sand washes through. Grout and concrete slurry don’t: they set in the pipe the same way they set on the floor, and water alone won’t wash out a lump that has gone hard.
Why we didn’t just blast it
Before we came back, an acid-based concrete remover had been poured down the ensuite waste to try to dissolve the grout. The plan on the return visit was to give it another go with the air snake to see whether the acid had softened anything.
Michael’s call was no. You don’t put compressed air down a line that has acid sitting in it. The safe way is to poke the blockage lightly with a hand tool and vacuum the waste out.
On the return visit the concrete debris still would not clear. The acid had not done enough to the grout.
The fix
The only real fix for set concrete in a shower waste is to get to it. We recommended cutting out the short section of pipe under the ensuite shower, removing the obstruction and reinstating the line. It is more work than anyone wants in a brand-new bathroom, but it is a known, one-off repair rather than a blockage that keeps coming back.
The camera footage made the conversation easy. Everyone could see exactly what was in the pipe and where, so there was no guessing about whether more jetting or more chemicals might do it.
Bought a new build? Read this
- A slow shower in a new home is worth checking early. Sand clears easily. Grout and concrete get harder to deal with every week they sit.
- Don’t pour acid down a blocked waste. It rarely dissolves set grout in a pipe, and it makes the next person’s job slower and more dangerous.
- Ask for the camera footage. If the cause is building debris, the footage shows it, which helps if you need to raise it with your builder.
If you have a drain that has never worked properly since handover, call 0499 281 430. We’ll camera the line and show you what’s in it before we quote.
More on blocked drains in Carine, or see more recent jobs.
