Legionella risk from unused hot water tank?
The hot water heater in my flat broke about two months ago (likely the element wore out, which happens about every 5-6 years). I was able to do without hot running water so I switched the heater off and tried to get a plumber to fix it but the unit (a Redring CT 75) turns out to be obsolete, so I've been looking at options for replacements. I never even thought about it until now, but in the meantime there's a 75 litre tank of unheated water stagnating as I haven't run the hot taps in the intervening period. Does this seem like a legionella risk? The tank is about 25 years old but seems sound, I believe it to be well insulated, room temperature has rarely been higher than 20C in the period, and I've not felt unwell. My cold water taps and shower which I use regularly are supplied from mains water.
I’ve now got a few replacement water heater options but some may take several more weeks to be installed. Either way, whenever a plumber does come round to drain and remove the old tank, I don’t want us both to be potentially exposed.
I’m aware I could just run the hot taps to empty the tank but am concerned in case this releases infected water droplets into the air. If I were to turn on the hot taps in the bathroom and kitchen and then shut the doors and stay out for 15 minutes while the tank empties, and then go back in with a face covering to turn the taps off, then aerate the rooms, then spray everything with antibacterial spray, would that make everything safe?