Tap water is drinking water which comes from an indoor tap or spigot. It is part of a larger indoor plumbing system which requires a complex supportive infrastructure including a stable water source, piping, and water filtration to keep the water safe.
Switching from bottled to tap water - Water safety FAQs - How safe is UK tap water?
UK tap water is among the safest in the world. Independent tests show UK tap water is among the safest in the world. The Drinking Water Inspectorate reported a 99.96% compliance with standards by UK water companies in 2006. Contamination is rare, usually caused by local pollution, such as old pipes, not the water supply.
Uk Restaurants urged to serve free tap water - Sim, é bastante comum clientes [patrons] pedirem uma jarra com água de torneira em restaurantes. Restaurants should offer free tap water - Restaurants are pushing diners into buying expensive bottled water, instead of offering them tap water for free, according to the Government's consumer watchdog. Some restaurants in Mayfair, London, are offering water at £50 a litre and even at chain restaurants a litre of water can cost £3.80. Nine out of 10 restaurants are pushing patrons to spend on so-called designer waters instead of serving free tap water, according to the National Consumer Council. Under the Supply of Goods & Services Act restaurants have to supply water along with a meal, but they are allowed to charge for it, even if it is just tap water. Only one per cent of restaurants in London always offer free tap water, before suggesting bottled.
Carbonated water (also known as club soda, soda water, sparkling water, seltzer, or fizzy water) is a blanket term for water in which carbon dioxide gas has been dissolved. This creates carbonation, or bubbles. Sparkling water may be plain, or may be flavored or have nutrients or salts added.
When in France… Drink Tap Water

That’s right, if you want to “do as the French do” on your next trip to Paris or Provence, better put down that bottle of Evian and grab a glass of cold stuff straight from the faucet. Sparkling water on tap is a fantasy come true... if I was to move to Paris tomorrow. I love fizzy water - can't get enough of the stuff - but, for reasons of temperance and economy, limit myself to one 750ml bottle per day (except weekends). But if I was to move to the 12th arrondissement I would have free unlimited access to ''La Petillante'' - literally, she who sparkles - a public fountain that gushes freely with chilled bubbles. How civilised is that?
Sep 22, 2010 – Eco-conscious Parisians can now get their sparkling water free and in unlimited supply at a new public drinking fountain installed by city authorities, which aims to wean consumers off bottled water and onto tap.
            Unveiled on Tuesday in the Jardin de Reuilly park in the east of the city by publicly owned water company Eau de Paris, the fountain injects carbon dioxide into regular tap water to make it bubbly, and chills it before delivering it to consumers. Separate faucets also provide a still version of the beverage, both refrigerated and unrefrigerated, and again pumped directly from the city’s own public water supply
Sources: The Guardian, The Telegraph and Reuters