Six weeks after moving in, a drain collapses under the garden path. The repair crew arrives, the excavator goes in, and the bill runs to around £7,000 — money the new owners hadn’t budgeted for, on a defect nobody flagged before they exchanged.

Standard homebuyer surveys — even the more thorough Level 2 and Level 3 RICS reports — focus on the structure above ground. What’s running beneath the garden, driveway, and floor slab is almost always left unchecked, leaving buyers exposed to expensive hidden defects that only surface once they own the problem.

Property Types That Warrant a Closer Look

Some properties carry a meaningfully higher risk of drainage defects, and it’s worth commissioning a survey regardless of what the standard homebuyer report says:

  • Homes built before 1970, which often still have the original pitch fibre pipes — a material prone to deforming and collapsing with age
  • Properties that have been extended or converted, where new drainage may have been tied into old pipework without proper inspection
  • Rural homes on private drainage systems, such as septic tanks or private pumping stations, which fall entirely outside the utility company’s responsibility

Visible Warning Signs Worth Investigating

A few signs during viewings are worth raising with the seller or your surveyor before you commit:

  • Slow-draining sinks, baths, or showers
  • Gurgling toilets or drains
  • Persistent damp patches that don’t correspond to an obvious roof or plumbing leak
  • White salt-like deposits (efflorescence) on basement or lower-ground walls, often a sign of long-term water ingress from a failed drain

Tree Root Damage

Certain trees are particularly aggressive toward buried pipework — oak, willow, poplar, and sycamore among them. As a rule of thumb, any of these species within 10–15 metres of a drain run deserves attention, since roots can extend beyond 15 metres from the trunk in search of moisture, and a hairline joint defect is often all the invitation they need.

What a CCTV Survey Actually Involves

A professional CCTV drain survey typically takes one to two hours on site. A camera is fed through the full length of the drain run, recording video and capturing images at every defect, with each one logged against the relevant industry defect code. You’ll usually have the full report — video, images, and a written summary — within a few days.

What Repairs Typically Cost

Knowing the likely repair cost before you exchange puts you in a much stronger negotiating position:

  • Root removal and clearance: £1,000–£3,000
  • Collapsed drains requiring excavation: £5,000–£10,000 or more, particularly where access is difficult

Timing Is Everything

A pre-purchase drain survey needs to happen before you exchange contracts, not after. Once contracts are exchanged, withdrawing from the purchase means losing your deposit — so any defect found afterwards is yours to pay for, with no room left to renegotiate the price or ask the seller to fix it first.

If you’re buying a property in Plymouth, Devon, or Cornwall, book a CCTV drain survey while you still have the leverage to act on what it finds.