Drainage disputes generally arise out of poor contractual documentation and/or defective work and/or materials.
Plans often lack critical detail and specifications are often general and not project specific. Roof, surface water, and waste water management systems are often inadequate and/or not practical to install as designed and changes are made to suit site conditions. Quotations will often omit (deliberately or accidentally) items of work but not expressly state so on their face and may contain estimates for the drainage work to be undertaken in the form of PC (Prime Cost) or Provisional Sums that are woefully inaccurate for the work that is in fact required to be undertaken. Ground conditions may vary across a site and may be more difficult to work in than expected (rock, buried rubbish, tree roots, other services etc) or unsuitable for the drainage system without considerable additional work being undertaken.
Head contractors/owners/engineers will often request changes to the scope of work and specification as work progresses, or changes to the pipe layout will be required to accommodate the as-built plumbing works and/or site conditions. Not all roof and surface water and/or waste water management systems will function as expected, some will be defective due to design error/oversight, and some will be improperly constructed or damaged during the construction process.
On the other hand, mistakes and errors are a feature of any building related work and some drainage contractors fail to have adequate quality assurance processes in place to ensure they achieve the agreed/specified scope of work to the specified standard, and/or to complete their work by the due date for completion.
In the circumstances, it is little wonder that drainage disputes arise from time to time. There are essentially two types of disputes that we deal with: