Is Drain Damage Accidental or Wear and Tear? What Insurers Look For

Drain damage counts as accidental when it was caused by a sudden, identifiable event, such as a pipe cracked by a heavy vehicle or broken by builders digging nearby. It counts as wear and tear when the pipe has deteriorated gradually with age, which is how most old drains fail. Many buildings insurance policies cover accidental damage to underground drains and exclude gradual deterioration, so the insurer's decision usually turns on evidence of cause, and that evidence normally comes from a CCTV survey.

Every policy is worded differently. What follows is how the distinction generally works in practice and what a survey can and cannot show. Your own policy wording decides what is covered.

What counts as accidental damage to a drain?

Accidental damage is a one-off event with a cause you can point to. The pipe was sound, something happened to it, and now it is broken.

Typical examples are a drain crushed under a skip lorry or a delivery vehicle driven over a garden, a pipe fractured by a contractor digging foundations or laying a new service, or a run broken when a fence post or a garden structure was driven through it. In each case there is a date, or at least a window of time, and a mechanism that explains the damage. On camera, damage like this often looks different from age-related failure: a clean fracture with sharp edges, a section broken at a point that lines up with the event above, and older, undamaged pipe either side.

What insurers usually treat as wear and tear

Wear and tear is deterioration that builds up over years. Most defects in older London drains fall into this category.

• Open and displaced joints in clay pipes, where the old mortar or early seals have failed over decades.
• Corrosion in cast iron pipework, common under Victorian and Edwardian houses.
• Deformation of pitch fibre pipes, which soften and lose their shape with age.
• Scale, fat and silt build-up that narrows the bore.
• Blockages on their own. A blocked drain is not damage to the drain, and clearing it is generally outside buildings cover, although some home emergency add-ons pay for it.

A survey report full of these observations, spread along a run and all at similar severity, describes a pipe that has aged rather than one that has been broken.

The grey areas: roots, ground movement and leaks

Some causes sit between the two, and this is where claims are most often disputed. Tree roots, ground movement and long-running leaks are treated differently from one policy to the next.

Roots enter through joints that are already open, so an insurer may argue the root is a consequence of wear and tear rather than the cause of the damage. A large tap root that has cracked a pipe wall is a stronger case than fine roots through a joint. Ground movement can be subsidence, which is usually a separate section of the policy with its own excess and its own rules, and a leaking drain can be both a result of movement and a cause of it. If your claim involves cracking to the building as well as the drain, expect the insurer to appoint a loss adjuster and possibly a structural engineer, and expect the drain survey to be read alongside their findings.

What a CCTV survey can show about cause

A survey records where each defect is, what type it is and how severe it is. It can support a conclusion about cause and timing. It cannot prove a date.

The useful evidence is in the pattern. A single fresh fracture at one point, directly under where a vehicle stood or a trench was dug, with sound pipe either side, points to an event. Defects repeated at joint after joint along the whole run point to age. Soil or stones inside the pipe at a break suggest the break is open to the ground. Every observation should be measured from a named access point, so the position of the damage can be matched to what happened on the surface. Where the route of the pipe is not known, drain tracing fixes it on a plan so the location of the damage can be shown relative to the building, the boundary and whatever caused it.

A report that says only "fracture, grade 4" does not help much. One that says where, how it relates to the surrounding pipe, and what it is consistent with, gives the loss adjuster something to work with.

Check who owns the damaged pipe first

Before any claim, establish whether the damaged length is your private drain at all. If it is a public sewer, it is the water company's to repair, not your insurer's.

Since October 2011, most shared drains and most pipework beyond a property's boundary in England have belonged to the sewerage undertaker, which in most of London is Thames Water. A pipe that serves only your property and sits within your boundary is normally yours. A pipe shared with a neighbour, or running under the pavement, normally is not. Our guide on how to tell a blocked sewer from a blocked drain shows how to work this out from the inspection chambers.

How to build the evidence before you claim

Record the pipe before anyone repairs it, and keep the record. Most disputes over accidental damage are lost because the evidence was dug up or jetted away.

• Tell your insurer early and ask whether they want to appoint their own contractor or accept an independent survey.
• Survey before cleaning or repair, unless there is an immediate risk to health or the building. If the drain has to be cleared first, say so in the report.
• Photograph the surface: the vehicle tracks, the trench, the sunken ground, the date the work took place.
• Keep the footage as well as the written report, with each defect's position measured and shown on a plan.
• Get the repair priced from the survey, so the insurer can see the proposed fix matches the defect found.

Our page on drainage surveys for insurance claims sets out what we include in a report prepared for an insurer or loss adjuster. If the survey shows ordinary age-related wear, we will say so plainly, because a report that stretches the facts tends to fail at the first question from the adjuster.