The challenge: Preventing stagnant water in storage tanks

摘要

The relatively recent Department of Health's Estate Facilities alert (EFA/2031/004) shows how changes in design and the inevitable wish to hold down prices can have serious side effects. The alert highlighted that some tank manufacturers have utilised hollow tubes to support the lids in sectional cold water storage tanks. These supports, which are held in position by internal bracings, can create stagnant water that may allow biofilm and slime growth. This contaminated water can harbour micro-organisms such as Legionella and Pseudomas. Forty years ago many medium-sized and larger water storage tanks did what they were designed for - they held water for many years. They were made up from 4ft square metal sections and were bolted together with a joint sealant. The strength of the side panels were given extra stability by bolting angle iron or similar strengthening ribs from a floor joint at 45° up to the side joint.