Is it safe to drink tap water from the bathroom?
It's three in the morning and you've just woken up with a mouth that's as dry as the Atacama desert. You desperately need to drink a glass of water, but should you trek downstairs to the kitchen or is it okay to top up at the bathroom tap?
It was drummed into me at an early age that the only water that was safe to drink is the cold water from the kitchen tap. Was this an old wives' tale and is this advice still relevant today?
Drinking the odd glass of water from your bathroom is unlikely to do you any serious harm (you brush your teeth with it don't you?) but the bathroom is almost certainly not the best source of drinking water.
Bathroom tap water can be supplied in a couple of different ways. In some houses the cold water tap in the bathroom will be supplied by the rising main, i.e. the bathroom tap is connected to the same supply pipes as the kitchen tap. In other houses, the water supply enters the house with the feed for the kitchen tap being very close to the stopcock. From the kitchen, the water makes its way up a supply pipe to a cold water tank in the loft which then feeds the upstairs taps, showers, toilet cistern etc. If it's an uncovered tank it might even contain a dead mouse, pigeon, or squirrel, yuk.
Your water supplier ensures that your drinking water supply is safe to drink by adding a disinfectant such as chlorine or chloramine (your water company can tell you which is used in your water). Chlorine is volatile and when chlorinated water is exposed to the open air (such as in the water storage tank) chlorine can escape leaving levels insufficient to kill harmful bacteria.
Many older houses have pipes that are made from lead. Lead doesn't corrode and is easy to bend and was therefore used extensively in UK plumbing until 1970. Unfortunately, lead is an incredibly toxic contaminant and a particular risk to children. When the health dangers were understood, lead pipes were banned. In older houses, the lead pipes between the mains water and the kitchen tap may have been replaced but there may still be dangerous pipes supplying the bathroom sink. If you are concerned about lead contamination then have your water tested.
Many households improve the quality of their tap water using a water filter. In the UK activated carbon filters are commonly used either in filter jugs or in filter taps. Filtered water is a great alternative to bottled water but your bathroom water is unlikely to be filtered. If you've paid for safe drinking water then why wouldn't you use it?
In the south and the east of England, many of the rivers that supply our drinking water run through limestone or chalk rocks giving rise to 'Hard Water'. This is perfectly safe to drink, it often has similar levels of calcium and magnesium to expensive mineral water.
Some people do not like showering or bathing in hard water and it can even aggravate skin conditions such as eczema and psoriasis. One solution to the problem is to install a water softener. Water softeners work by exchanging calcium ions for sodium ions. In areas such as London, water softening can lead to levels of sodium which may be unhealthy to drink. In areas where the water is very hard, the kitchen sink tap is often left unsoftened.
What about Hotels?
When you stay in a hotel you really have no idea of the quality of the tap water. Sure there may be a 'potable water' sign in the bathroom but is it really safe to drink? Has the water travelled through lead pipes or been stored in a tank? If the overpriced mineral water in the mini-bar is not for you then maybe the best solution is to bring a bottle of water from a trusted source.
Whilst on the subject of which taps are safe to drink from, it's worth mentioning that it's never a good idea to drink from the hot water tap. The hot water is often stored in tanks that can be heated and cooled many times and could lead to the growth of bacteria such as legionella. Steer clear of the hot tap and always choose the cold water tap.
So, is it safe to drink tap water from the bathroom? Probably not. It's unlikely to kill you but the clean water from the cold tap in your kitchen is a far better option. If you're prone to needing a drink in the night then maybe keep a fresh glass of kitchen tap water on your nightstand.