Even the 'take shorter showers' advice is interesting, they could advise people to skip a few and flush the toilet only after having a 'number two'.
Recently I had the water board out to investigate a leak. Earlier in the year, before there was any hint of drought, I had been pressure washing the green mould off my late father's house, leading to a lot of water usage. And yes, I did use a lot of water then, far more than could be saved by skipping showers, using the dishwasher instead of hand washing crockery and by only boiling the water I needed for tea, nevermind deleting emails.
There will always be some that consume water at an entirely different scale to others, there needs to be a pricing mechanism for this beyond the metering they have now, where everyone gets an allowance for their basic needs and those watering gardens, washing cars or power-spraying houses pay considerably more. There will be