Tap water temperature: 10 to 15 degrees

Reading time: ~10 minutes

How many degrees is tap water in the Netherlands?

If you turn on the cold tap, water flows out at roughly 10 to 15 degrees Celsius. That figure comes from Vitens, which supplies around 5.8 million people in the Netherlands. It's no coincidence that the margin is so narrow: most of our drinking water comes from groundwater, and the temperature of groundwater stays between 10 and 13 degrees all year round, according to Brabant Water. The soil acts as a huge buffer that flattens out the seasons.

It's also true that the spread at home feels bigger than 10 to 15 degrees. Once the water enters your home, it passes through pipes that run through a crawl space, a utility cupboard or a heated floor. If it sits there overnight, it takes on the temperature of its surroundings. That's why the first sip from a tap you turn on in the morning is often noticeably more lukewarm than the water that comes out ten seconds later.

At PureFilter we see customers ask that question almost always in summer, and almost always in combination with taste. Lukewarm water tastes flatter, and chlorine and metallic tastes stand out more at higher temperatures.

The maximum temperature: 25 degrees, and why

There's a hard upper limit. The Drinking Water Decree (Drinkwaterbesluit) stipulates that drinking water in the pipe network may be a maximum of 25 degrees. WML puts it this way: the law sets that limit, and during a prolonged heatwave a local exceedance is sometimes unavoidable. In that case it's considered force majeure, and the water remains fit for use. The Human Environment and Transport Inspectorate monitors this.

The reason for exactly 25 degrees is microbiological. According to Dunea, the legionella bacterium multiplies mainly in water between 25 and 45 degrees that has been standing still for a longer time. RIVM therefore applies a double rule of thumb for installations: cold water no warmer than 25 degrees, preferably below 20, and hot water no colder than 50 degrees, preferably above 60. Everything in between is the zone you want to avoid.

That limit is under pressure, though. PWN had research institute KWR calculate what happens to the pipe network under the KNMI climate scenario WH'23 for 2050. The outcome: if nothing changes, the temperature in 12 percent of the pipes will exceed 25 degrees. A striking detail from that same PWN study: in green neighbourhoods, drinking water stays noticeably cooler than in paved-over city centres, because vegetation absorbs the heat instead of the soil.

Is there also a minimum temperature?

No. There is no statutory lower limit for cold tap water, for the simple reason that cold poses no health risk. Cold water is actually beneficial: the colder it is, the slower bacteria multiply. It's not for nothing that RIVM names "preferably below 20 degrees" as a target value for the cold water side.

For hot tap water there is a practical lower limit, though. Vitens advises setting the thermostat of a boiler or combi boiler with a storage tank to at least 55 degrees. Brabant Water uses 60 degrees as the temperature at which the legionella bacterium is killed. If you turn a boiler down to save energy, you're setting it right in the middle of the growth zone.

If you live in a rented home and your hot water is consistently lukewarm, that's a matter for the landlord, not something to experiment with yourself.

Why the temperature fluctuates in your home

Soil temperature and pipe depth

The soil around the pipe determines almost everything. PWN puts it sharply: close to the source, the pipes are large and the water flows fast, so the temperature is almost the same as that of the source. The further into the pipe network, the narrower the pipes and the longer the water sits still, and the more the temperature creeps towards the soil temperature. Laying pipes deeper, from 1 to 1.5 metres, is one of the measures PWN has calculated.

Standing still in your own home

The stretch of pipe between the water meter and your kitchen tap is your responsibility, and that's where most of it happens. Water that sits still for a night or a holiday takes on the temperature of the crawl space, the shaft or the utility cupboard. Evides warns that a poorly ventilated utility cupboard, for example after you've put equipment in it, can cause the tap water to warm up.

City or greenery

It matters where you turn on the tap. In residential areas and business parks with little greenery there are already far more hotspots than in rural areas, according to PWN, and in heavily urbanised centres the risk of warmer drinking water is greatest. Same source, different address, different temperature at the tap.

Transit time of the network

Vitens reports that there are only 24 to 48 hours between the production of drinking water and delivery from your tap, and that the water in their pipes doesn't stand still. That short residence time is exactly why the temperature in the public network stays so stable, and why problems almost always arise indoors.

Tap water in winter and in summer

In winter the top layer of soil cools down and the temperature at the tap drops towards 5 to 10 degrees. In severe frost it can turn out lower, especially for pipes that lie shallow or run through an unheated crawl space. Pleasant to drink, less pleasant to hold your hands under, and your washing machine needs more energy to heat it up.

In summer it goes the other way: 15 to 20 degrees is then normal, and after a night of standing still in a warm pipe it rises higher. That's the moment when people start calling their water "lukewarm" and "flat". The water is still safe, but the taste experience does change. If you want to know whether that warm water is actually safe to drink, read why it's better not to drink hot tap water.

If you notice that suddenly no water or very little water comes out of the tap, something other than temperature is going on. In that case, our overview of what to do if there's no tap water will help you get further faster.

How hot is hot tap water from the tap?

Hot tap water usually comes out of your boiler or combi boiler at between 55 and 60 degrees, and cools slightly on its way to the tap. At the tap itself, 50 to 55 degrees already feels very hot: at those temperatures a burn risk arises within a few seconds, which is why many shower taps have a limiter.

More important than the exact figure is this: hot tap water isn't meant for drinking. Evides explains that too many metals can be dissolved in hot tap water, such as copper from a storage tank or from copper pipes, and that taps on the hot water side can release nickel, chromium and cadmium. Dunea gives the same advice. If you want hot water for tea or cooking, draw it cold and heat it in a kettle or pan.

A boiling water tap is the exception. According to Evides, it has a stainless steel storage tank close to the tap, so no copper is absorbed into the water. If you have such a system and wonder what's left to filter, our page on the water filter for a Quooker explains how the two relate to each other. In short: a boiling water tap controls temperature, not purification.

Tap water that's too warm: when is it suspicious?

Rule of thumb: cold water that still clearly stays lukewarm after thorough flushing deserves attention. If it stays lukewarm after running for a minute, the warmth isn't in a stagnant bit of pipe but is structural, in your installation or in the network.

Warm, stagnant water is exactly the environment in which bacteria thrive best. You can read what can grow there and what that means in our explanation of faecal bacteria in tap water. Good news in advance: according to Vewin, Dutch drinking water meets the quality standards in 99.9 percent of all measurements.

What temperature does to taste, limescale and filtering

Temperature doesn't change the composition of your water, but it does change how you taste it. Warmer water holds onto less dissolved oxygen and therefore tastes fuller and flatter. Volatile substances such as chlorine are released more easily at higher temperatures, so you smell and taste them sooner. The same applies to a metallic aftertaste from older pipes.

Limescale works the other way round. Calcium carbonate actually dissolves less well as water gets warmer, and that's exactly why limescale build-up collects in your kettle, boiler and coffee machine and not in your cold water pipe. How hard your water is varies strongly by region; our overview of water hardness per municipality shows where you stand.

An under-sink filter sits on the cold water pipe, and that's deliberate. That's where the water is coldest, most stable and microbiologically most favourable. The PureFilter Mineral+ removes more than 100 contaminants there, including PFAS, microplastics, heavy metals, nitrate, medicine residues and chlorine, and adds magnesium, calcium and potassium back in via the Swedish Mineral Rock™. The system is certified to NSF 42, 53, 61 and 372. If you first want to understand what a water filter does and doesn't do to your tap water, that page is the best place to start.

To be clear: a filter doesn't make your water colder. What it does do is remove the taste and odour substances that stand out most with lukewarm water. Anyone who'd rather not keep a jug or bottle in the fridge therefore chooses a permanent solution from the filters that fit under your sink.

The installation itself is easier than you'd think: the filter goes between the cold water pipe under your sink and the tap itself, in 5 to 10 minutes and without tools. Step by step, it's covered in our guide to installing a water filter.

All temperatures side by side

Frequently asked questions

Conclusion

Tap water temperature in the Netherlands is normally between 10 and 15 degrees, with 5 to 10 degrees in winter and 15 to 20 degrees in summer. It legally may not exceed 25 degrees, and that's not an arbitrary number: that's where the zone begins in which bacteria multiply. If your cold tap stays lukewarm after flushing for a minute, that's the signal to look further into your indoor plumbing.

For most households, temperature is ultimately a matter of taste, not safety. Dutch tap water meets the standards in 99.9 percent of measurements. What lukewarm water does do is bring chlorine, metallic tastes and other residues more clearly to the fore. Anyone who wants to solve that without refilling jugs ends up with a permanent filter on the cold water pipe: €149.00 one-off, then €65.00 a year for a replacement filter, which works out at less than one cent per litre. With 40 days' free returns and a 5-year guarantee, you can try it risk-free.