Diagnosis
CCTV Drain Surveys Explained
What a drain camera can and cannot see, when a survey is worth paying for, and how to read the footage you're shown.
Tree roots
Tree roots do not break sound, sealed drain pipe. They grow towards moisture already escaping from a joint that has opened or a crack that has formed, then enter through that defect and thicken inside the pipe, catching debris until the drain blocks. This means roots are a symptom of an existing pipe fault rather than the original cause. Cutting them out restores flow but does not remove the pathway, so they typically return within one to three years unless the entry point is sealed or the section replaced.
The common mental image — a root wrapping a pipe and crushing it — is close to backwards.
Roots grow where there is water, oxygen and nutrient. A sound sealed pipe offers none of those to the surrounding soil: the water is on the inside and the wall is continuous. Roots have no reason to grow towards it and no way in.
What happens instead is that a defect appears first. A mortar joint degrades. Ground movement pulls a joint slightly open. A hairline crack develops in ageing pipe. Now a small amount of moisture and warm water vapour escapes into the soil around it — and in a dry Auckland summer, that is the most attractive thing in the vicinity.
Fine root hairs grow towards the source and find the gap. Once inside, conditions are ideal: permanently moist, nutrient-rich, protected. The root thickens. More follow it in. Within a few seasons there is a mass hanging inside the pipe like a net, and everything that passes — paper, fat, solids — catches on it.
If roots were the cause, removing the tree would be the fix. Because the defect is the cause, removing the tree changes nothing about the pipe — and other roots, from a neighbour's tree, a hedge, or even shrubs, can find the same opening.
Three factors line up almost perfectly here.
Ageing jointed drainage. Pre-1960s Auckland housing was drained with glazed earthenware or concrete pipe laid in short lengths — roughly 600mm — and sealed at every joint with mortar. That is a potential entry point every two feet along the run. Modern uPVC uses long lengths with rubber-ring seals, which is why newer properties rarely have this problem.
Clay soils that move. Much of Auckland sits on clay that shrinks through a dry summer and swells again when the rain returns. Over decades that seasonal movement works jointed pipe out of alignment, opening gaps that were sealed when laid. It also explains why root blockages so often have a seasonal rhythm.
A mature urban canopy. The suburbs with the oldest drainage are also the ones with the most established street trees, planted through the same era. The two problems are geographically identical.
Add a mild, wet climate with a long growing season and you have close to ideal conditions for root intrusion.
The vigorous water-seekers we encounter most are liquidambar, plane, willow and poplar, along with large established natives and, at smaller scale, hedging like privet and photinia. Worth knowing: the tree does not have to be anywhere near the drain. Root systems routinely extend well beyond the canopy, and we regularly find intrusion from trees ten or more metres away — frequently on a neighbouring property or a council berm.
Geographically, the heaviest root work is through the older central suburbs — Ponsonby, Mt Eden, Epsom, Remuera, Newmarket and Onehunga. The eastern bays including Orakei, Saint Heliers and Mission Bay show the same pattern, as do the older parts of Takapuna.
Out west through Henderson, Massey and New Lynn, and south through Papakura and Manurewa, larger sections and heavier clay produce a variation on the theme: more ground movement, more displaced joints, and roots exploiting the gaps that movement creates.
A CCTV survey confirms it definitively and, more usefully, shows the entry point — which is the thing you actually need to know.
Mechanical cutting or jetting with a root nozzle clears the growth and restores full bore. This is the right immediate step and it will get your drain working. It is treatment, not cure — the pathway is still open, and regrowth typically takes one to three years depending on species, proximity and the size of the opening.
Foaming products exist that slow regrowth in the pipe. They are a maintenance measure with a limited life and they need repeating. They do not seal the defect. Worth knowing before paying for something occasionally marketed as a permanent solution.
This is the actual fix in most cases, and root intrusion is close to the ideal application for it. A resin liner cured inside the existing pipe seals every joint and crack along the relined section, removing the pathway entirely. Where the pipe barrel is sound and only the seals have failed — the classic older-Auckland pattern — a short relined section can end a decade of recurring blockages without digging up the garden. See drain repair and relining.
Where roots have caused or accompanied genuine structural failure — a collapse, severe deformation — the section has to come out and be replaced.
Add up what clearing the same drain has cost you over the last five or six years, then compare it with sealing the entry point once. For many Auckland properties the repair has already paid for itself. For others — a minor intrusion that has never actually blocked, an imminent sale — periodic clearing is the better call. Either is legitimate; the point is to decide with the numbers in front of you.
Usually not, and often you cannot anyway.
Removal does not repair the drain. The defect remains, and other roots can find it. If the tree belongs to a neighbour or sits on a council berm, removal is not your decision. And many established Auckland trees are protected — Auckland Council administers tree protection rules through the Unitary Plan, with some trees scheduled individually, so it is worth checking with the Council before making plans.
In the large majority of cases, sealing the pipe is faster, cheaper and far more certain than dealing with the tree — and it keeps a mature tree that is doing a lot of good in a city street.
Typically one to three years, depending on the species, how close it is and how large the opening is. A big gap near a vigorous liquidambar can re-block within a year. A fine intrusion at a tight joint might go several years.
Usually not for the drain itself. Most policies treat root intrusion as gradual deterioration rather than sudden accidental damage. Resulting damage to the building from an overflow is more often covered. Check your wording, and keep the CCTV footage — insurers generally want evidence of cause.
The drain is your responsibility if it is on your side of the point of supply, regardless of whose tree it is. That feels unfair and is nonetheless the general position. It is also worth remembering that the roots got in through a defect in your pipe — which is the part you can actually fix.
Copper sulphate is sometimes recommended online. It is not a repair, its effectiveness in a flowing drain is limited, and there are real environmental concerns about putting it into the wastewater network. Salt does very little. Neither addresses the entry point.
Far less often. uPVC uses long lengths with rubber-ring seals, so there are fewer joints and they are far more resistant. Roots can still enter where a joint was poorly assembled or the pipe has been damaged, but it is uncommon compared with earthenware.
Not usually, until it blocks completely. If the drain is still flowing you have time to get it surveyed and make a considered decision. If wastewater is backing up or the gully is overflowing, that is an emergency.
Tell us what it is doing and we will tell you what it probably is, what it takes to fix, and what that should cost.