In most residential settings, a simple assessment may show that the risks are low and no further action may be necessary. (An example of a typical lower risk situation may be found in a small building (eg housing unit) with small domestic-type water systems, where daily water usage is inevitable and sufficient to turn over the entire system; where cold water is directly from a wholesome mains supply (no stored water tanks); where hot water is fed from instantaneous heaters or low volume water heaters (supplying outlets at 50 °C); and where the only outlets are toilets and wash hand basins). If the assessment shows the risks are low and are being properly managed, no further action is needed but it is important to review the assessment regularly in case anything changes in the system.
Where showers are installed, these have the means of creating and dispersing water droplets which may be inhaled causing a foreseeable risk of exposure to legionella. tenants should be advised to regularly clean and disinfect showerheads.
It is important that water is not allowed to stagnate within the water system and so there should be careful management of dwellings that are vacant for extended periods (eg student accommodation left empty over the summer vacation). As a general principle, outlets on hot and cold water systems should be used at least once a week to maintain a degree of water flow and minimise the chances if stagnation. To manage the risks during non-occupancy, consideration should be given to implementing a suitable flushing regime or other measures such as draining the system if it is to remain vacant for long periods.