Can you drink the tap water?

Who tests it, and how often

There are two sets of checks, and they are independent of each other.

• The network operator (ACEA, Hera, Talete and others, depending on the area) tests the water along the whole route: at the source, in the treatment plants, in the reservoirs and in the distribution network.
• The ASL, the local health authority, carries out external checks with its own samples, and has the power to declare the water unfit to drink.

Dozens of parameters are analysed: microbiological (Escherichia coli, enterococci), chemical (nitrates, arsenic, metals, pesticides, disinfection by-products) and indicators such as hardness, pH and conductivity. If a value goes over the legal limit, the town council issues an order restricting or banning drinking use: it is a public act, not a private message.

Where to read the figures for your own water

You do not have to believe anyone, sites selling purifiers included. The data is public:

• On your operator's website, usually in a «water quality» section where you search by town or by street. It is the most up-to-date source.
• On the bill, where many operators publish the average figures for the year.
• From the town council or the ASL, for orders and external checks.

When you open them, the four figures that say most about everyday life are: hardness (how much limescale there will be), dry residue (how many dissolved salts there are), sodium and nitrates. The others matter, but they either stay within the limit or an order follows.

So why do so many people buy water?

For reasons that have almost nothing to do with whether it is drinkable, and they are worth stating plainly, because this is where the decision is actually made.

• The taste. The chlorine used to keep the water safe along the network can be tasted, and many people do not like it.
• Habit. Italy has been buying bottled water for decades and for many households it is simply what has always been done.
• Sparkling water. It does not come out of the tap, and those who drink it have to buy it.
• Doubt about the pipes in the building, which unlike the public network are nobody's responsibility to test: past the meter, the plumbing belongs to the owner.

What a purifier changes (and what it does not)

This is the part where an honest seller differs from a dishonest one.

It does not change whether the water is drinkable. Mains water is already drinkable: a domestic purifier does not make it so and must not be sold that way. Anyone using coloured test kits or alarms about the network to convince you is doing something the Italian competition authority has already penalised in this sector.

It changes the composition and the taste. A reverse-osmosis system lowers the dry residue considerably, removes the chlorine and with it its taste, and then remineralises. The result is lighter water with a consistent taste.

It changes the convenience. Drinking water, sparkling too, from a tap at home instead of from a crate carried up the stairs. For most people who switch this is the real reason, and there is nothing wrong with saying so.