Do you worry about an elderly relative scalding themselves when making a drink ?
This applies especially to someone with sight loss.
I bought one of these handy water level indicators for my Mother in Law when she had glaucoma and very poor sight.
They hook over the side of a mug, cup or bowl and beep when the liquid reaches the desired level. That is a safe level to add milk or not to overflow and scald themselves.
Known as the “audible/vibratory indicator” this costs £6.65 and is certainly worth buying for someone who struggles to see how much boiling water they are pouring.
Another great alternative although much more expensive is the one mug water boiler.