Yes this is true.. Another thing that people don't usually consider is that any hot water system actually contains a gradient of temperatures, all the way from

Yes this is true.. Another thing that people don't usually consider is that any hot water system actually contains a gradient of temperatures, all the way from whatever your water heater is set at, down to almost room temperature where the faucet is. Somewhere along that gradient is the temperature that Legionellae will thrive, so it's a good idea to let the hot water run until it comes up to temperature before using that water.