Just turn on the tap and water will come out. We use it every day for drinking, cooking and personal hygiene. But there's still one question hanging in the air: is this water actually safe to drink?

The answer is a bit of a complicated one: the water that leaves the treatment plant meets the national standards for 'safe water'; but the water that reaches your tap may not be the 'clean water' you imagine.

It's a long and complicated journey from the source to the tap. Next, we'll take a good look at the facts about household water quality.

First stop: the water source – where it all starts.
Tap water doesn't just appear out of thin air, does it? It comes from rivers, lakes, reservoirs, and groundwater. The quality of the water at the source is the most important thing that affects the final water quality.

Pollution risks: Things like industrial wastewater, runoff from fertilisers and pesticides, domestic sewage and even naturally occurring heavy metals can all contaminate water sources. These pollutants include organic compounds, heavy metals, pathogens, antibiotics, and other micropollutants.

Here's the current situation: Even though there are protective measures in place for water sources in China, water source environments in some regions still face challenges. Water source pollution is still the main problem with tap water treatment.

The next stop is the water treatment plant, where we'll find out how standard 'safe water' is produced.
The main job of a water treatment plant is to turn raw water into drinking water that meets the national 'Sanitary Standards for Drinking Water' (GB 5749-2022). This standard is really strict, covering 97 water quality parameters. The treatment process usually goes something like this:

Coagulation and Sedimentation: When you add coagulants to raw water, tiny suspended particles and colloidal matter clump together to make bigger particles, which then settle out.

Filtration: The water is passed through layers of filter media, like quartz sand and activated carbon, to get rid of finer impurities.

It's important to disinfect things properly. This is the most important step! Chlorine gas or sodium hypochlorite is usually used to disinfect the water, getting rid of bacteria, viruses and other microorganisms to make sure the water doesn't get contaminated again during distribution.

At this point, the water leaving the treatment plant should meet the national standard for 'safe water'. So where does the problem lie? The problem comes up at the 'last mile' to your home.

The third stop is the water distribution network, where there's a risk of 'secondary contamination' along the long journey.
Tap water has to travel a long way through a lot of underground pipes to get to people's homes. These pipes, which are often in service for decades, are a major threat to water quality.

Pipe ageing and corrosion: Cast iron and galvanised steel pipes can get rusty and covered in scale if they're not looked after. Things like rust and sediment can flake off into the water, which can make it look yellow or cloudy.

Residential Water Tanks and Reservoirs: A lot of high-rise buildings need extra pressurisation for their water supply, using tanks or reservoirs. If these facilities aren't managed properly or not cleaned and disinfected quickly, they can become breeding grounds for bacteria, microorganisms, sediment and insect eggs, which can lead to severe secondary contamination.

The fourth stop on our journey is your household tap, where we'll reach the final truth.
After water has travelled all the way to your home, there's always the chance that something might have gone wrong with the water quality along the way.

Just to let you know, there are still some concerns about residual chlorine. To stop bacteria, chlorine levels in water need to stay at the right level at the point of use. This explains why tap water sometimes has a 'bleach-like' smell. Chlorine can sometimes change the taste and smell of water, but it's usually safe if the levels are within the recommended limits. If you leave it on too long, it can release a carcinogen called chloroform.

Scale Deposits: The white residue that appears on kettles is caused by calcium and magnesium ions forming when they're heated, which is a sign of 'hard water'. It's pretty much harmless, but it can reduce how well your boiler is working, change the taste of your water, and even make your skin dry.

Things like odour, discolouration and impurities: These usually come from secondary contamination in water distribution networks or communal tanks, and they're a pretty clear sign of poor water quality.

A simple way to check the quality of household water
Take a look at: Fill a clear glass with water and check it against light for any bits in the water. Leave it undisturbed for a few hours to check for sediment at the bottom.

Take a sniff – is there a distinct chlorine smell (like bleach) or other unusual smells (like earthy or musty)?

Taste: Sip some boiled water to see if it's got a strange taste or smell. If it's a bit stringy or heavy (maybe you've got hard water) or if it tastes like metal (maybe you've got old pipes), then you'll know.

Inspect: Have a look at your kettle to see if you've got any hard water stains on the base.

Here are the conclusions and recommendations for household drinking water.
So, is tap water clean? It's generally safe for everyday use, like washing and cleaning, but it's not recommended for drinking straight from the tap, especially in older estates or high-rises.

Here are some ideas to keep your family's drinking water clean:

Boiling for consumption: It's the most economical basic method. It's great at getting rid of microorganisms, but it can't handle chemical contaminants like heavy metals, limescale or microplastics.

Installing a water purifier: This is the best household drinking water solution right now – it's reliable and convenient.

Pre-filter: Just install it at the main water inlet and it'll filter out the big stuff like silt, rust and insect eggs, keeping your pipes and appliances clean.

Drinking water system for when you're using it So, in the kitchen, you've got two main options for purifiers: reverse osmosis (RO) and ultrafiltration. The RO option gives you pure water that's good to drink straight away, and it gets rid of most of the contaminants, even heavy metals. The ultrafiltration option keeps the minerals but can't get rid of the heavy metals. It's up to you which one you go for, depending on the quality of the water where you are.

It's important to keep communal water tanks clean. As the property owner, you can ask the management to carry out regular cleaning and maintenance of secondary water supply facilities.

So, there's no need to worry too much about the quality of tap water, but it's important to have a clear understanding of the situation. If you understand its journey and the risks involved, and you put in place a suitable household solution to purify it, you can really protect your family's drinking water.

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