Why you might be drinking tap water, cooking your pudding and even brushing your teeth incorrectly… according to little-known government advice

Maybe you’re drinking tap water all wrong.

Not only that, you could also be boiling your spuds and brushing your teeth incorrectly.

Little-known government advice is urging us to change our tap water habits to reduce the risks of exposure to substances that can harm our health.

These include never using cooking water from the hot tap, even if it is just to fill your boiling pan.

Here, MailOnline shares the guidelines that you probably had no idea about from the Drinking Water Inspection (DWI)…

Never drink from the hot tap or use it for cooking

Compared to boiling the kettle, using water straight from the hot tap to cook or make a brew seems like an easy time-saving hack.

But the DWI warns that people should only use the cold water tap from their kitchen for drinking and cooking.

This is because hot tap water carries a greater risk of becoming contaminated with metals such as copper and lead, both of which can have immediate and long-term health effects.

Although most homes no longer have lead pipes, the DWI still recommends against consuming water from the hot tap because the water may contain elevated levels of other metals.

Even using such water for cooking, such as filling a pot to cook potatoes faster, is not recommended, as boiling will not remove potential metal traces.

The DWI states: ‘Please note that you may only use cold water from the kitchen for drinking and cooking.

‘Water from the hot tap is not recommended for drinking as it may contain high levels of metals such as copper, which gives the water an astringent taste.’

Do you live in an older house? Let the tap run until it turns cold before drinking anything

Exposure to lead in household water can harm the mental development of children and cause kidney and heart problems in adults.

The concern is so great that the use of the heavy metal in household pipes has been banned since the 1970s.

But the DWI warns that some homes in Britain may still contain the metal and people should be aware of the potential risk.

Even modern homes are not necessarily safe, as unqualified plumbers or do-it-yourself renovators may have used lead solder in the past, the material used to join two metal pipes together.

The DWI says the easiest way for people to check if they have lead pipes in their home is to find the shutoff valve.

If the pipe is dull gray with a swollen joint next to the faucet and the metal turns a shiny silver when you gently scrape it with a coin, chances are the pipe, and possibly other pipes in the home, are made of lead.

Once lead is found, the DWI advises people to run the faucet they use for drinking and cooking before using it to remove the liquid that has been in the pipe for a long time and result in higher lead levels has.

The DWI says this is usually enough water to fill a dish sink or until there is a noticeable drop in water temperature, indicating it is “fresh” from the electrical outlet.

However, it is emphasized that this is only a temporary measure and that lead pipes or solder should be replaced as soon as possible.

Avoid drinking and even brushing your teeth with water from the upstairs taps, if you have a storage tank in your roof

Thirsty at night?

Be warned: it may not be safe to fill a glass of water from the upstairs tap.

By the same logic, brushing your teeth with the bathroom tap can also be risky.

According to the DWI, many older homes get their water upstairs from storage tanks in the roof or attic.

Although modern, updated versions of these tanks are now considered safe to drink, many older models have problems.

Some are too large, meaning the water inside can ‘remain’ for too long, making it technically not fresh enough to drink.

Other tanks are made of traditional metals that can rust over time, releasing bits of metal into the water – albeit in trace amounts.

Tanks must also meet a number of strict standards, such as having filters to prevent pests from entering and not being placed near a heat source that can cause the water to spoil more quickly.

The DWI says the easiest way to check if the upstairs faucet is connected to a water storage tank is to run the faucet fully and place your thumb under the spout.

If you can hold back all the water this way, it’s probably being fed from a tank rather than the mains.

What do the experts say?

Professor Alan Boobis, a toxicology expert at Imperial College London and government adviser, said he personally does not follow the DWI advice to avoid metals in tap water, but stressed it is sensible.

“Some substances are likely to be higher in the water first drawn from the tap, for example if they are leaking from the pipes,” he said.

‘There would be no harm in following this advice, and it could well help to reduce levels of some substances, even though they are likely to be below levels of concern anyway.’

Professor James Coulson, a toxicology expert at Cardiff University, said he, like many Britons, was unaware of the government advice but was following his own precautions.

“Personally, I run the tap for about 30 seconds to make sure the “dead space” in the system has been flushed and visually inspect and smell it before drinking,” he said.

“But that’s just my personal preference.”