Let’s talk about water filters

Getting water from the filtered water tap

Water is a miraculous element! It’s is an important basis of all life. Without it, we would not be here.  In fact, we are 60-80% water!

In order to keep those levels, we need to constantly replenish our bodies with water. Overall, it is recommended to drink four to six cups a day. That’s roughly around 2 liters.

Apart from drinking it, there’s a lot of things we do with it at home. We cook with it; use it to wash ourselves and our clothes, dishes, and other things. We water our plants and we even like to swim in it and play with it.

Why would you want to filter your water?

Obviously, you want to filter your water if it is dirty; be it sand, silt or rust.

It’s important to note, however, that not every water is equal. Waters from lakes and springs have a different composition of minerals than the water coming from the public water system. To guarantee that no bacteria thrive, it is often disinfected with chlorine. It can also contain other things you don’t necessarily want to ingest.

Then there is also so-called ‘hard’ and ‘soft’ water. Hard means that the mineral content is high, while ‘soft’ means the opposite. Hard water is not a good friend to your appliances that use it. Minerals can build up, making them work less efficiently

Water can also be polluted by bacteria or chemicals that can make you sick.

Drinking water

As a strong opponent of buying bottled water, I like to get my water directly from the tap. In Germany, where I am from, the water from the tap tastes good.

But here, in Barcelona, the water got a funny taste of chlorine although it’s said that it is safe to drink. I don’t like to drink this water from the tap as I believe that it still poses a health risk.

For this reason, we started with a 5 phase reverse osmosis filter system in our kitchen. The water tasted great again!

Reverse Osmosis

Reverse osmosis is a system that lets the water pass through a semi-permeable membrane. It is effectively removing fine impurities: minerals, salts, fluoride, mercury, sulfate and many more.

But, this procedure comes at a cost. It wastes between 5 and 20 liters to filter 1 liter of water.

While we had this system installed in our home, we first used the wastewater to water our plants. We quickly realized that it is not doing them any good and then only used it for cleaning.

After 1 year, we came to the conclusion that reverse osmosis is not very good for our health either. It is purifying the water indeed so much, that we lose on the minerals our bodies need.

So we simply removed this one filter from our system. Now we have a 4 stage system: one sediment filter and four activated carbon filters.

Polypropylene water filter

Also known as sediment filter. It removes bigger particles such as dirt, silt, and sand.

This is the first filter in our system, protecting our next filters.

Activated Carbon

Those filters are able to remove a long list of contaminants in your water. The carbon is very porous and also slightly positively charged. Because of this, particles and molecules are getting stuck. Activated carbon can remove sand, dirt, rust, chlorine, pesticides and herbicides and many other chemicals (but not all of them).

Most notably, activated carbon filters clear the water of bad tastes and odors. But it’s important to understand that activated carbon filters do not work well with hot water.

Our system has 3 different carbon filters, getting incrementally finer. And that’s all we need, here in Barcelona.

There are two more types of filters I’d like to present to you.

Ceramic filters

Similar to activated carbon, ceramic filters are porous and filter out larger particles than the size of the pores. This way ceramic filters can also remove sand, dirt, silt, rust and some bacteria.

They are cheap simple to install and easy to clean.

UV Filters

Bacteria and viruses can be sneaky. They are the main reason municipalities chlorinate their water in order to kill them. If your water supply is not chlorinated, the bacteria and viruses that are small enough, don’t get filtered out by activated carbon filters. But they do get removed by reverse osmosis.

To save water and keep it pure, UV filters can be applied. Ultraviolet light is able to disinfect the water by up to 99.9 %.

Energy costs are also fairly low as a filter consumes as much as a 60 W lightbulb.

Personal hygiene

Did you ever think about the purity of the water you shower with? Think about it, your skin is the biggest organ you have and your lungs taking the fourth spot on the list. Both are directly in contact with the water you shower or bathe yourself with.

Hot water opens the pores of your skin and you breathe in the water vapor. While chlorine is not well absorbed by our skin (even with open pores), it is irritating to your eyes and skin. Think about swimming in a chlorinated pool, your eyes start to sting after a while.

Chloroform, a by-product of chlorinated water can enter our systems through inhalation. Chloroform in municipal water is suspected to be carcinogenic. There are other risk factors to be considered as well.

Should you shower with or bathe in chlorinated water, you might want to also filter the water you shower and bathe with.

Finding the right filter for the job can be tricky. Not all hold true to their claim. For instance, activated carbon filters do a great job, however, as we learned already, they only work with cold water. It’s therefore important to install those filters before the water reaches the water heater.

Good shower filters can remove 90% or more of the chlorine but others none at all. It’s a good idea to make sure that the filters have been tested by independent entities.

But maybe you don’t want to filter your shower water or you can’t. Here  are other things you can do already to reduce exposure:

But maybe you don’t want to filter your shower water or you can’t. Here  are other things you can do already to reduce exposure:

  • take shorter showers/baths
  • don’t shower/bathe with hot water
  • turn the water off while soaping yourself


Depending on what you intend to clean, you want water of certain purity. In most cases,  we don’t need to filter the cleaning water. But you might have experienced that cleaning with hard water can leave white streaks or leaving your clothes stiffer than they should be. In this case, a ceramic or activated carbon filter can help to reduce the mineral content of the water.


It’s important to know where your water is coming from and what comes with it. The job of the municipalities is to keep the water contamination free. Yet, they might be using chemicals you don’t agree with.

If you think you can live a healthier life by installing a water filter, it’s definitely worth investing the time to do the research. And find the one that fits best to you. There’s not a single solution that fits all cases. And they all come with different grades of efficiency and cost.

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