Highgate Infrastructure Changes: Aging Pipes at Risk
City of Unley · Council intelligence · Last updated April 2026
“CONSERVATION GRANTS 2025/2026 - SECOND ROUND... Council approve a Conservation Grant of $2,227.00 for maintenance pruning of a significant tree at 35 Carlton Street, Highgate.”
Full Council, 23 March 2026
Arborists working on a big established tree on Carlton Street means root disturbance is a real possibility — and in a street with older clay sewer pipes, that's worth watching. If you're on or near Carlton Street and your drains start running slow after this work kicks off, don't wait on it.
“Administration work with staff from the City of Adelaide and the City of Burnside to investigate the provision of improved walking and cycling infrastructure along the southern boundary of the Adelaide Park Lands fronting Greenhill Road from Anzac Highway to Fullarton Road.”
Full Council, 23 March 2026
Greenhill Road runs right along Highgate's northern edge. When councils start investigating footpath and cycling upgrades on a busy road like that, groundworks follow — and groundworks near the boundary mean potential disruption to older mains and stormwater infrastructure feeding into the suburb. Keep an eye on it.
Highgate is a quiet pocket of Unley with older housing stock — which means ageing clay pipes, cast iron connections, and hot water units that have been running on borrowed time. Council is currently looking at infrastructure changes along Greenhill Road, which cuts close to the suburb and can put pressure on older services nearby when the digging starts. There's also arborist work approved for Carlton Street — tree roots and old pipes in the same street is a combination worth knowing about.
Highgate's housing era — late 50s through 70s — means you're almost certainly dealing with clay sewer lines, cast iron, or galvanised steel. Those materials did their job, but they're not young anymore. If you're seeing slow drains, wet patches in the yard, or backing up water after rain, tree roots and silt are the usual culprits. Start by checking whether you're on a shared or single sewer line and how old the spouting is — stormwater flooding the system is easier to rule out than you'd think. When Council's digging around Greenhill Road or arborists are working Carlton Street, older water and sewer lines nearby get jostled. Pressure spikes, new leaks in weak spots, blockages that shift. If you're in Highgate and something goes wrong mid-work, it's not always random — infrastructure activity matters. Check whether any council projects are scheduled near your street before you assume it's just old age.
- Tree root intrusion into clay sewer lines on Carlton Street and other tree-lined streets — established gardens and old shallow pipes are a guaranteed problem waiting to happen
- Stormwater pooling against foundations on the flatter allotments in the south end of Highgate — clay soil, minimal fall, water sits for days after rain like the April downpours
- Slow or blocked drains in 1950s–70s terrace and villa homes — combined sewers, silt buildup, roots all working together to strangle flow
- Hot water unit failures in systems that haven't been replaced since the early 2000s — Highgate's got dozens of units running on borrowed time
- Leaking or heavily corroded galvanised water mains under older concrete slabs and footings — the metal's just gone, pressure drops, water quality suffers
- Blocked or failing spouting and downpipe connections — water diverting into the wrong places, foundation seepage, gutters that sag and pool instead of draining
- Pressure surges and burst pipes during City of Unley's Greenhill Road infrastructure works — construction near older service lines can spike demand and damage weak spots
- Cast iron connection corrosion at sewer junctions — especially where clay pipes meet cast iron fittings, rust blooms and blockages follow
- Septic or on-site effluent issues in Highgate homes not connected to main sewer — older treatment systems failing, no maintenance history, Council scrutiny increasing