By Matthew Baring-Gould, Kingscliff-based drainage plumber. Servicing Tweed Heads for 4 years. 5.0 stars across 173 Google reviews. Licensed NSW 383340C and QLD 15036450. ABN 74 605 392 348.

Blocked sewer at a Tweed Heads property with the only accessible point under the house. Gained access there, extended the hydrojet downstream, cleared the blockage. CCTV found no tree roots but the camera read 9 degrees uphill at the junction, which means the pipe is backfalling and holding water. Earthenware pipe laid in 1.2 metre lengths is prone to shifting in the ground. Advised monitor-and-call-back; no callback, so assuming it is flowing.

What the customer called us for

Owner called us out for a blocked sewer at a Tweed Heads property. The only accessible point on the sewer was under the house.

What we found when we got there

We gained access under the house, extended the hydrojet downstream, and hit the blockage. After the jet pass, we ran the CCTV camera through the line. No tree root ingress, no cracks or displacement visible. The camera did show a 9-degree uphill reading at the junction leading in, which indicates the pipe is backfalling at that section and holding water and effluent above the junction. Pipework in the ground was earthenware, laid in 1.2 metre lengths, so there is always room for movement as the ground settles compared with 6 metre lengths of PVC.

Why we did it this way

A 9-degree backfall at a junction will hold water and solids. Over time, toilet paper and effluent cannot clear the dip and the blockage comes back in the same place. On earthenware that is laid in short 1.2 metre lengths, shifts in the ground are normal and accumulate over decades. The honest advice here was: it is clear now, monitor it, and if it comes back we excavate and relay the section with the correct fall. Jetting the same spot again every year is not the right answer.

What we did on site

1. Gained access to the sewer line from under the house.
2. Extended the hydrojet downstream to the blockage.
3. Cleared the blockage.
4. Ran the CCTV camera through the line.
5. Confirmed no tree roots or cracks, found a 9-degree backfall at the junction.
6. Documented the backfall and explained the earthenware-shift cause.
7. Advised the owner to monitor and call back if it recurs.

The result

Line clear on the day. Owner has a camera report and knows exactly where to look if the blockage returns. No callback received, so assuming the flow has held.

If you have the same issue

If your sewer blocks at the same spot every year or two and the camera shows clean pipe but a slight uphill reading, it is almost always backfall. The jet clears it but the dip refills with solids. Relaying that section with correct fall is a one-off fix. Call Matty on 0447 188 394 or request a quote.

Customer names and addresses have been withheld. Individual results vary. Drain Masters Plumbing is licensed in NSW (383340C) and QLD (15036450).

Frequently asked

How does the camera read fall?

The CCTV head has an inclinometer that measures the pitch of the pipe as it moves through. A good sewer line reads a gentle downhill number. A dip reads uphill at one end and downhill at the other. Nine degrees uphill at a junction is a clear backfall.

Why does earthenware pipe shift more than PVC?

Earthenware was laid in short 1.2 metre lengths with a joint at every section. PVC comes in 6 metre lengths with far fewer joints. More joints means more places for the pipe to shift as the ground settles and moves over the decades.

Should I relay a 9-degree backfall straight away?

Not necessarily on the first blockage. If the line otherwise looks clean on camera, monitor it. If it returns in the same place, that is the signal to excavate and relay that section. There is no point digging up a line that might flow for another ten years.

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