For the storage, retention, or reuse of rainwater, metal tanks must withstand suspended solids and potential contaminants. Galvanizing can work well in outdoor or agricultural systems, while epoxy and vitreous enamel coatings offer greater resistance when prolonged exposure to or the presence of chemical agents is anticipated.

Cylindrical tanks are the most common solution for large volumes in industrial and civil engineering projects, while rectangular tanks are useful in limited urban spaces or for integration into Sustainable Urban Drainage Systems (SUDS).