I think you will find in the UK only the cold water tap in the kitchen is direct from the mains, traditionally the bath and wash hand basin cold feed was from the attic tank.
Not in any of the houses I know. There is no reason to include a tank in the pressure system in the mains supply. this will usually supply all cold taps and WC cisterns. The only deviation from this would be a garden tap which requires a non-return valve upstream of the final faucet to prevent siphon back issues.
Some modern plumbing solutions are direct feed cold and mains pressure hot with a small header tank to flush toilets, but they are not usual, most plumbers don't bother with attic tanks for flushing toilets if fitting combi boilers, and connect direct to the main feed.
My point exactly. The only tanks are usually for gravity fed hot water systems with an additional (steel/plastic) tank to top up the intergral copper tank on the hot water tank. The other tank is to top up any losses in the central hot water system.
So I maintain that contrary to your view, no drinking water passes through a tank in the house, (unless you are in the habit of drinking water from the hot water system).
However we are now getting WAY off topic.