I feel like letting the water flow for a few seconds, and maybe rubbing round the spout of the tap with a wet finger, is good enough safety-wise. My main problem is almost all public was basins I see have mixer taps with no way make it 100% cold. I’m not keen on drinking water that’s been through the boiler/heating system as those things always look manky inside, it makes sense to me that more (or more dangerous) microbes might be present in the warmth, and it tastes bad anyway.