Whilst manholes are necessary, they are hugely susceptible to problems like leaks. Being exposed to the weather and to erosion and damage from road traffic, they can also suffer from problems with the equipment that they are housing, like the pipes that manage sewage and manage the flow of water. If these pipes leak, the water can only go upwards, where it will be eventually forced up out of the manhole, causing surface water and flooding.

Situations in which leaks can occur include:

• Dry joints – when new cement has been placed on top of old cement, creating a void between the two where leaking water can gather.
• Incorrectly sealed water-tight joins
• Damaged, corroded or cracked pipes
• Old, damaged or faulty valves can leak water
• Old or worn manhole covers that do not properly seal off the manhole.