Daniël Mostert v Cape Town City Council

The appellant, Mostert, operated a furniture shop (Furni-Scene) in Parow. On 18 December 1990, a water main belonging to the Cape Town City Council burst under Voortrekker Road, causing extensive flooding of Mostert's premises and damage to stock valued at R307,458. The pipeline in question was a 62km cast-iron water pipeline constructed in 1921, running from the Steenbras reservoir to the Molteno reservoir. The pipeline consisted of approximately 17,600 cast-iron pipes, each weighing about two imperial tons. About 37km of the pipeline ran under roadways in built-up areas, much of it under Voortrekker Road carrying heavy traffic. Between 1974 and 1982, the pipeline had been internally lined with cement to limit corrosion, an expensive process only undertaken for pipelines considered basically sound. The pipeline had experienced various bursts over the years: in 1950, 1963, 1964, 1970, 1972, 1974, 1979, 1981, 1982, 1983, 1987, and 1990. Some had identifiable causes (defective couplings, contractor damage, operational error), while others remained unexplained. In 1981, after a burst, Professor Ball (a metallurgist) examined specimens and concluded the cast-iron was in good metallurgical condition and that the failure was likely due to extraneous impact or soil movement rather than corrosion.

• Whether the Council was negligent in failing to replace large parts of the pipeline or regularly test it under pressure
• Whether the Council was negligent in not insuring itself against claims by property owners
• What caused the 1990 burst - inherent defects in cast-iron or inadequate design for modern traffic loads
• Whether the doctrine of res ipsa loquitur applied to establish negligence
• What remedial measures, if any, should the Council reasonably have taken to prevent such bursts
• Whether the pipeline had reached the end of its useful life and required replacement
• The standard of care owed by a municipality in maintaining water infrastructure
• Whether new evidence of subsequent bursts in 1995 should be admitted after judgment was reserved

Appeal dismissed with costs, including costs for two counsel. The trial court's finding that Mostert had not established negligence on the part of the Cape Town City Council was upheld. The application to admit new evidence of subsequent bursts was refused.

A municipality is not liable in delict for damage caused by a burst water main unless negligence is proven. Negligence requires proof that: (1) the municipality failed to foresee a reasonable possibility of harm, or (2) having foreseen such possibility, failed to take reasonable steps to guard against it. What steps are reasonable depends on four considerations: (a) the degree of risk created; (b) the gravity of possible consequences; (c) the utility of the conduct; and (d) the burden of eliminating the risk. Where the cost of preventive measures (such as replacing infrastructure) is grossly disproportionate to the actual losses suffered or reasonably foreseeable, it is not negligent to refrain from taking such measures. The occasional failure of cast-iron pipes due to inherent active cracks or various extraneous causes does not in itself establish that a pipeline is below standard or that the owner has been negligent, particularly where expert evidence establishes the pipeline remains metallurgically sound with adequate safety factors. A municipality has no duty to insure against liability it has not incurred; imposing such a duty would amount to absolute liability, which requires legislative intervention. The doctrine of res ipsa loquitur does not apply where expert evidence establishes that the type of incident in question can and does occur without negligence.

Schutz JA observed (at paragraph 39) that if it were established that the pipeline had moved from the stable "plains" of the bathtub curve to the final upward slope indicating end of useful life, "very different considerations might apply" and it might become unreasonable not to accept the cost of replacement. This suggests that municipalities have an ongoing duty to monitor aging infrastructure and may be required to replace it once it demonstrably reaches end of useful life, even at significant cost. The Court also made observations about the admissibility of new evidence after judgment is reserved, reiterating the principles from Oosthuizen v Stanley and Mkwanazi v Van der Merwe. The Court emphasized the need for finality in litigation, noting that admitting evidence of events occurring after the relevant period would not assist in determining what the municipality should have foreseen at the material time. The Court noted that the evidence of old cracks found in the 1995 bursts actually appeared consistent with the Council's case rather than supporting Mostert's theory. Schutz JA made the colorful observation (at paragraph 43) that leading a large volume of water under pressure across densely populated land under the municipality's exclusive control "is the equivalent of walking ones tiger across the forum" - suggesting the inherently hazardous nature of the activity, though this did not alter the legal conclusion that negligence must still be proven.

This case is significant in South African delict law for establishing important principles regarding municipal liability for infrastructure failures. It clarifies that: (1) Municipalities do not bear absolute liability for damage caused by infrastructure failures - negligence must be proven; (2) The test for negligence in infrastructure maintenance requires balancing the foreseeability and gravity of potential harm against the cost and practicality of preventive measures (applying Kruger v Coetzee); (3) A grossly disproportionate cost of prevention compared to actual losses will defeat a negligence claim; (4) The doctrine of res ipsa loquitur does not apply where expert evidence establishes that the type of failure can occur without negligence; (5) Statistical clustering of incidents does not necessarily establish causation if the clustering falls within the range of random probability; (6) Municipalities cannot be required to insure against liability they have not incurred, as this would amount to imposing absolute liability, which is a matter for legislative intervention; (7) The case illustrates the court's approach to aging public infrastructure, recognizing that inherent characteristics of materials (like cast-iron) may cause occasional failures without necessarily indicating the end of useful life or requiring wholesale replacement. The judgment is important for defining the limits of municipal liability and the reasonable expectations placed on local authorities in managing public infrastructure, particularly in balancing public safety against fiscal constraints and the interests of ratepayers generally.