Reading time: ~8 minutes
Short answer
No, drinking hot water directly from the tap is not recommended. Hot water remains stagnant in your boiler and pipes, where metals such as copper, lead, and nickel dissolve faster, and where bacteria grow at temperatures between approximately 25 to 50 degrees Celsius. All Dutch drinking water companies advise: use cold tap water and heat it yourself with a kettle or pan.
A glass of hot water with lemon in the morning, quickly making tea with the hot water tap, or preparing baby formula with lukewarm water from the mixer tap: it seems convenient, but it's not a good idea. In the Netherlands, only cold tap water is officially considered drinking water. Hot water from the tap does not fall under this category, and this is due to what gets into the water along the way. In this guide, we explain why, what the exact risks are, and how you can ensure you have pure, great-tasting water at home.
Table of Contents
What do we mean by hot tap water?
Definition
Hot tap water is water that comes from your hot water appliance, i.e., your boiler, geyser, or central heating combi boiler. It has been heated and has therefore stood in your plumbing system at an elevated temperature. From that moment on, it no longer meets the quality requirements for drinking water, even if you let it cool down later.
The distinction is important. Drinking water companies deliver water that meets strict legal standards up to your water meter. From your cold water tap, this water generally comes out unchanged. However, as soon as water enters your hot water circuit, it passes through a boiler and separate pipes where water quality can no longer be guaranteed. Lukewarm water from the mixer tap also counts: that is partly hot water. At PureFilter, we observe that many people are unaware of this difference and use the hot water tap purely for convenience.
Why is hot tap water not recommended?
Drinking water companies such as Vitens, WMD and Waterbedrijf Groningen all advise against drinking hot water directly from the tap. There are three main reasons for this.
1. Metals dissolve faster in hot water
This is the most important reason. Metals dissolve better in hot water than in cold water. Hot water from your boiler and pipes can therefore contain higher concentrations of copper (from copper pipes and the storage tank), lead (in older homes with lead pipes), and nickel, zinc, iron, chromium, and cadmium (from taps and fittings). Lead, in particular, is harmful, especially for young children and pregnant women, as it can affect brain development even at low concentrations.
2. Bacterial growth at lukewarm temperatures
Water that stands for a long time at a lukewarm temperature is an ideal breeding ground for bacteria. According to the RIVM, the Legionella bacterium multiplies best at temperatures between approximately 25 and 50 degrees Celsius. This is precisely the range for water in parts of a hot water circuit that is more lukewarm than truly hot. Legionella is only killed above 60 degrees Celsius. Water coming from the hot water tap that has been somewhere in between can therefore contain more bacteria than fresh cold water.
3. Loss of oxygen and taste
Heating the water reduces its oxygen content and can alter its taste. As a result, hot tap water often tastes bland or slightly metallic. In some systems, this process can also lead to the formation of undesirable substances such as nitrites. In short, the water loses precisely the freshness that makes cold tap water so appealing.
Tap water and temperature: what happens?
Temperature is the key to this whole story. The table below shows what happens to your water quality at different temperatures.
| Temperature | What happens | Advice |
|---|---|---|
| Below 25 degrees (cold tap water) | Little dissolution of metals, hardly any bacterial growth; official drinking water | Safe to drink |
| 25 to 50 degrees (lukewarm water) | Optimal growth zone for legionella and other bacteria; metals dissolve faster | Do not drink |
| 50 to 60 degrees | Bacterial growth slows down, but metals continue to dissolve in the boiler | Do not drink |
| Above 60 degrees | Legionella is killed, but the water has already been in the boiler for a long time | Only for domestic use, not as drinking water |
Important to know: even cold tap water can contain slightly more metals if it has been stagnant for a long time. Therefore, let your cold tap run for a while if no water has flowed through the pipe for more than a week, for example after a holiday. Rinsing for half a minute until the water feels cool is usually sufficient.
Why cold (and filtered) water is better
Cold tap water in the Netherlands is of high quality and meets legal standards. However, cold water can also contain traces of substances that just do not exceed the standard or that are added through your own house pipes, such as PFAS, microplastics, drug residues, and heavy metals. Those who want to be on the safe side and at the same time want tastier water, opt for filtration on the cold water supply.
The PureFilter Mineral+ water filter is connected under the counter to the cold water pipe, precisely the tap you should already be using for drinking water. The 5-stage system removes more than 100 contaminants up to approximately 99 percent, including lead, copper, PFAS, microplastics, chlorine, and drug residues. The filter is NSF-certified to standards 42, 53, 61, and 372. Afterwards, the Swedish Mineral Rock™ adds magnesium, calcium, and potassium, so your water not only tastes pure but also softer and richer.
Please note: a water filter is intended for the cold water pipe and does not solve the problem of hot tap water. The solution for delicious hot water remains: draw cold (filtered) water and heat it yourself with a kettle or pan.
Points of attention and misconceptions
- Hot water with lemon: the morning routine is fine, but draw cold water and heat it with a kettle instead of using the hot water tap.
- Tea and coffee: always use cold water that you heat yourself. The hot water tap or lukewarm water from the mixer tap is not suitable.
- Baby food: never prepare bottle feed with hot tap water. Boil fresh cold water and let it cool down to the correct temperature.
- Boils faster: lukewarm water from the mixer tap seems convenient because it boils faster, but the health risks do not outweigh this.
- A Quooker: a boiling water tap with a stainless steel reservoir does not release metals into the water and is therefore an exception. However, a Quooker does not remove PFAS or heavy metals from the supplied water.
Comparison: hot, cold, and filtered water
| Feature | Hot tap water | Cold tap water | Cold filtered (PureFilter) |
|---|---|---|---|
| Official drinking water | No | Yes | Yes |
| Risk of dissolved metals | Increased | Low | Very low (lead/copper filtered out) |
| PFAS and microplastics | Possibly present | Possibly traces | Up to ~99% removed |
| Bacterial growth during stagnation | Increased risk | Low | Low |
| Taste | Often bland or metallic | Fresh | Fresher, softer, more mineral-rich |
| Suitable for drinking | Not recommended | Yes | Yes, with extra assurance |
Pure water from your cold tap
The PureFilter Mineral+ filters 100+ contaminants and adds minerals back. Installation in 5 to 10 minutes, without a plumber.
View PureFilter Mineral+What can you do yourself?
The practice is simple. For drinking, cooking, and hot beverages, always use cold tap water and heat it yourself. Let the cold tap run for a while if the water has been stagnant for more than a week. If you also want to remove the last traces of PFAS, heavy metals, and microplastics and have tastier water at home, an under-sink filter is the logical next step.
The PureFilter Mineral+ starts from €149.00 including the first filter, and a replacement filter costs €49.90 for a whole year, approximately €0.14 per day. One filter provides about 15,000 to 20,000 liters of pure water. You can install it yourself in 5 to 10 minutes without a plumber, and thanks to 40 days free returns and a 5-year warranty, you run no risk. Are you unsure which model suits you best? Then check out our guide to the best water filter.
Frequently asked questions
Is it dangerous to accidentally drink hot tap water?
One sip of hot tap water is generally not immediately dangerous for a healthy adult. The advice is preventative: daily consumption of hot tap water increases exposure to metals such as lead and copper, which you want to avoid, especially for children and pregnant women.
Can I use hot tap water to make tea or coffee?
No, always use cold water that you heat yourself with a kettle or pan. Hot water from the tap can contain more dissolved metals, and boiling it will not remove those metals.
Why is lukewarm water from the mixer tap also not recommended?
Lukewarm water is partly hot water and is often in the temperature range of 25 to 50 degrees Celsius, where bacteria grow best. Moreover, it is mixed with water that has passed through the boiler. Turn the mixer tap fully to cold for drinking water.
Can a water filter solve the problem of hot tap water?
No. An under-sink filter like the PureFilter Mineral+ is connected to the cold water line and therefore improves your cold water. The rule remains: draw cold (filtered) water and heat it yourself.
Is hot tap water from a Quooker safe?
A Quooker has a stainless steel reservoir and therefore does not release metals, which is an advantage compared to a regular boiler. However, a Quooker does not filter PFAS, microplastics, or heavy metals from the incoming water. A filter on the cold water supply complements this.
Why do I sometimes need to flush cold tap water?
If water has been stagnant in the pipes for longer than approximately a week, even cold water can dissolve slightly more metals. In this case, let the tap run for half a minute until the water feels cool; then it's fresh again.
Conclusion
Drinking hot water directly from the tap is not recommended. In your boiler and pipes, metals such as lead and copper dissolve faster, and at lukewarm temperatures between 25 to 50 degrees Celsius, bacteria grow best. All Dutch drinking water companies therefore advise the same: use cold tap water and heat it yourself. If, in addition to this basic rule, you also want to remove the last traces of PFAS, microplastics, and heavy metals and have fresher water, then a filter on the cold water supply provides that extra assurance.
Ready for pure, mineral-rich water?
The PureFilter Mineral+ purifies and mineralizes your cold tap water. Starting from €149.00, with 40 days free returns and a 5-year warranty.
Discover PureFilter Mineral+