Over time due to natural weathering, corrosion, boat transportation, and carrying sewage the canals deteriorate (see Canal Degradation) and collect sediment. This requires maintenance in the form of dredging. Other surrounding accessible Urban Elements are maintained during the dredging process. Elements usually maintained simultaneously are Canal Walls, Sewers, some components of Bridges, and if accessible Utilities.
Dredging is the process of cleaning the bed of harbors or waterways by removing silt and rubbish with a dredge. There are two methods used to dredge the canals of Venice:
Disposal of Sediment
disposal of sediment is not a simple process that can be captured accurately. It includes transporting exported sludge to a treatment plant where further testing and treating occurs. The sludge is categorized and treated accordingly. For more information see Sedimentation.
After dry dredging of a Canal there are strict dimensions that the Canal must fit before being re-flooded. This dimension, refereed to by Venetians as Rio Profilo "Teorico" da Norme, translates "Canal Theoretical Profile Rules". Because in dry dredging the Canal must be completely emptied this offers a great opportunity to reconstruct the dimensions of the Canal in order to ensure safe passage of boats, an optimal placement of the Gatoli Outlets and a sloping of the canal floor to defer sediment build up. All depth measurements of the Canal dimensions are measured based on a reference point called "the Mareographic Zero". 
- ↑ The Building Blocks of Venice:Preserving knowledge of a city's infrastructure and maintenance. Worcester Ma. Worcester Polytechnic Institute.2011 
- ↑ Insula Spa http://www.insula.it/