On Finding & Mapping Drinking Water Sources using OpenStreetMap

I do not know about you, but I usually have a water bottle with me regardless where I go. I love to refill whenever possible. I dislike buying bottled water in countries where perfectly fine drinking water comes out of the tap.

It boggles me how in Europe they charge for water in cafes and restaurants. Also, it is considered not appropriate to ask for tap water in those places. Currently, I am in New Zealand and they provide you with free water in most places like libraries, cafes and restaurants. (The same goes for toilets by the way. I have never seen so many public, clean and free toilets as I did here in New Zealand.)

Being away for home, on travel or on multiday hikes, I will run into the need of refilling my water bottle(s) eventually. In this post I am going to show you how I find drinking water on a map called OpenStreetMap (OSM).

OSM is an online map which can be edited by anyone. It's kinda like Google Maps and Wikipedia combined. Since it is free and very detailed, OSM provides the data behind a lot of map apps like Komoot, MAPS.ME or OsmAnd Maps (I prefer the latter). It excels in every application except car navigation and easy search. But in many countries it's probably the best resource to find drinking water, if you know how to look for it.

What to look for?

To search OSM one needs to understand how OSM represents objects on the ground, for example a water tap or a well, using tags.

Map features and tags

In order to describe a physical feature on the map, OSM uses tags consisting of a key and a value. For example, a place to get drinking water from is tagged with the key amenity (facilities used by people) and the value drinking_water. A feature usually has a primary tag stating the main use and many secondary tags to describe additional properties. So far so good... If that was the only tag needed to find drinking water sources this post would end here - but there are other tags which represent sources to get drinking water from. More on them next.

Note: In OSM tags in use and their meaning have evolved over time. Both their usage and meaning can very depending on their context.

First lets have a look at the most important and common one: Map features (primary tags) representing drinkable water sources are mainly amenity=drinking_water, man_made=water_tap or natural=spring.

The most important additional property (secondary tag) is drinking_water=yes (amenity=drinking_water implies dinking_water=yes).

There is also man_made=water_well and man_made=spring_box for structures which are used to get access to groundwater and to catch water from natural spring respectively.

Let's have a look at all the possible tags related to drinking water in OSM below. The descriptions were taken directly from the OSM wiki.

Drinkable (primary tags)

amenity=drinking_water: A drinking water source which provides potable water for consumption
amenity=water_point: Places where you can get larger amounts of "drinking water" for filling a fresh water holding tank, such as found on caravans, RVs and boats
man_made=water_tap: Publicly usable water tap
man_made=drinking_fountain: Provides a small jet of drinking water; Usage discouraged. amenity=drinking_water should be used instead. fountain=* can be used to describe to type of type of fountain (e.g. fountain=bubbler or fountain=drinking).
natural=spring: A place where ground water flows naturally from the ground

Drinkable (secondary tags)

drinking_water=yes: Indication whether a feature provides drinking water
drinkable=yes: Usage discouraged. drinking_water=yes should be used instead.
drink=*: Describes if (and optionally how) a certain drink is available at an amenity or shop
fountain=drinking: For generic drinking water fountains
fountain=bubbler: For fountains which slightly jet the emitted water in the air for purpose of easy drinking

Maybe drinkable

man_made=water_well: A structural facility to access ground water, created by digging or drilling
man_made=spring_box: A structure designed for protecting and catching groundwater from a natural spring; Usually in combination with natural=spring

Probably not drinkable

amenity=fountain (Primary feature): A fountain with cultural, decorative, or historical significance or which serves a recreational purpose; Additional property could be fountain=drinking
watering_place (Primary feature): A place where water is contained and animals such as horses can drink

How to search?

Here comes the hard part. Now that we know what to look for, the question is how do we look for it? There is not a single way to do it, and none are as user-friendly as typing something into Google Maps, but they are more powerful.

overpass turbo

Following query to the overpass turbo service will find every possible drinking water source in your area-of-interest. Go ahead and execute this query on the overpass turbo website.

[out:json];
(
  node[amenity=drinking_water]({{bbox}});
  node[amenity=water_point]({{bbox}});
  node[man_made=water_well]({{bbox}});
  node[man_made=spring_box]({{bbox}});
  node[man_made=water_tap]({{bbox}});
  node[man_made=drinking_water]({{bbox}});
  node[fountain=drinking]({{bbox}});
  node[fountain=bubbler]({{bbox}});
  node[natural=spring]({{bbox}});
  node[drinking_water=yes]({{bbox}});
  node[drinkable=yes]({{bbox}});
);
out body;

Note: node stands for features which are represented on the map as a point instead of a line or polygon. bbox stands for bounding box, which is the visible part of the map displayed on the overpass turbo website.

Next step could be to export these points and open it in your favorite map app. Of course that is a tedious process, but might be worth it depending on what you are going to do.

OsmAnd Maps

The complexity due to the sheer number of possible tags and combination of these is the reason why many apps, like the ones I listed in the introduction, typically hide tags from the user and present them with simple categories which can be displayed on the map. Of course, behind the scenes, these categories are just a set of tags. Sometimes it is not possible to do complex searches containing a custom selection of tags in those apps. In OsmAnd Maps one can create custom categories by clicking on the search symbol, then on Categories and after scrolling all the way down on Add custom category. Unfortunately, it's still mediated by what map features (tags) OsmAnd Maps choose to display to the user. On the Add custom category screen you can select Drinking water, Water point, Water well, Spring and Water tap (just search for water and spring) to be combined in to one category which you can display on the map anytime in the future.

In most cases like touring a city or traveling in a van it is sufficient. For a multiday hike though, I like to get a comprehensive list of all possible water sources using the overpass turbo serve with the query of the previous chapter.

How to map?

Now that we know how to search for drinking water places what happens if we stumble upon a new place in the real world which is not on the map yet? The beauty of a crowdsourced and open licensed project like OpenStreetMap is that we can contribute to it and improve it for everybody coming after us!

To add a new place to the map you need an OSM account. The easiest way to map is to use the ID editor in the browser. Alternativly you can also use apps like OSM And Maps (Android and iOS) or OsmoTagger (iOS only). For instructions of how to map using OSM please have a look at the guide by learnOSM.

Lets have a look at which tags some types of drinking water sources should have.

How to tag a drinking water fountain?

Drinking water fountains have as primary tag amenity=drinking_water. If the fountain emits a jet of water into the air you can use the tag fountain=bubbler. That is it! Easy as pie.

If the feature offers an easy way to fill a bottle one can add the tag bottle=yes.

How to tag a water well or spring box?

German forest accommodates many stone and wooden structures to catch groundwater from a natural spring, so called spring box or spring catchment. In Germany they are called Quellfassung but we usually just say Brunnen. But we use Brunnen also for water wells, which leads to confusion and possible mapping errors (at least I was confused). The difference between those two structures is that water "just flows" out of a spring box whereas water needs to get pumped out of water wells.

In OSM the tag (man_made=water_well) marks places for accessing groundwater. Spring boxes are mapped with man_made=spring_box. In the later case a combination with natural=spring usually makes sense.

In both cases drinking_water=yes or drinking_water=no can be used. There is also drinking_water=conditional to state that the water seems drinkable. If there is a label "No drinking water" because there is no official control, you can add the tag drinking_water:legal=no.

Another interesting additional attribute related to springs is seasonal=no/yes/winter/....

Appendix

That is all from my side. If you know of more relevant tags or interesting information regarding drinking water sources in OSM, please share it!

In general the best resource about anything related to tags is usually the OSM wiki together with taginfo.

In Germany there is also a great initiative called Tip Tap to get places like restaurants and pharmacy to offer free refill of water bottles, put them on the map and end the feeling of not being welcomed to ask for drinking water at those places. "If an establishment (café, bar, etc.) participates in a water refill network – indicated by a visble sticker or sign" use the tag drinking_water:refill=yes.

Might the Map be with you!

Thanks to Maike, my partner, for proof reading this post, despite being very possible a boring post.

Published 2024-11-17