Out of sight and out of mind: the impact of drainage on commercial property investment.
There are compelling reasons to routinely have a Pre-Acquisition Drainage Assessment as a standard part of Due Diligence when investing in commercial property.
Drainage Liabilities & Investment Returns

Suitable and effective drainage is a fundamental requirement of any commercial property investment. Hidden from normal view and often overlooked, drains have the potential to produce liabilities which can interrupt investment cash flows. Although some costs can be recouped from the tenants' service charge, in some cases, shared infrastructure and the provision of pollution prevention measures such as oil interceptors may fall to the landlord. Pollution remediation following tenant vacancy, bankruptcy or even through attacks of vandalism may incur large financial costs to the landlord thus knowing the suitability of prevention measures and precautions should be a necessary part of investment decision making and Due Diligence.