- 1 Standardising & Entering Distributed Water Points
- 2 Review of Water Point Tagging in southern Africa
- 2.1 Summary
- 2.2 Aim
- 2.3 Scope
- 2.4 Method
- 2.5 Main Results
- 2.6 Discussion of major keys with many alternatives
Standardising & Entering Distributed Water Points
Water & sanitation points are often recorded in OSM for a variety of reasons. This database is likely to be very useful in relief situations, but without a systematic tagging scheme it is difficult to quickly find the information required. Development and presentation of a suitable system could allow clearer tagging and more efficient understanding.
Thomas Hills has been looking at current tagging methods and possible improvements. Tallguy (Nick Allen) has been looking at suitable methods for cross-referencing water point data from external repositories such as the Humanitarian Water Point Data Exchange. This page is meant as a means of communication between OSM users and water point experts to develop a standardised water point tagging method, and a method of cross-referencing water point data using that method.
There is already a page on Water, Sanitation and Hygeine (WASH) on the OSM wiki but it hasn't been updated in a long time. The embryonic ideas there have been partially included in this page. There are HOT tagging presets for various water point types but these have not been updated for about four years.
Suggested project steps
As this is meant to be a collaborative process, this project plan is only a suggestion, and comments and criticism are welcome!
- Observe & review current tagging methods to identify what water point information OSM contributors wish to enter into the map
- Develop a preliminary standardised tagging procedure which accommodates the relevant information
- Send procedure out for review by OSM contributors and water experts
- Modify procedure based on feedback
- Send preliminary water point cross-referencing procedure for review
- Modify cross-reference procedure based on feedback
- Launch water point cross-reference programme.
Current tagging methods
There is a great variety of tagging methods for water points, partly due to their heterogeneity and partly due to the lack of an existing clear tagging method. A survey of features with the tag amenity=drinking_water was performed across southern Africa - the results and discussion are shown on a [separate page]. Over 3441 water points, 156 different keys were used. Many were similar to those used on other nodes in the survey, and the tags could be grouped according to the kind of information they conveyed, as shown [here].
Preliminary proposal for a tagging protocol for water points in OSM
The table below sets out the current preliminary proposal for tagging water points in OSM. It is suggested that water points, used for more than simply drinking water, are tagged as amenity=water_point.
|OSM Location Keys|
|geometry||This specifies the type of feature||node|
|id||The OSM ID|
|coordinates||This provides the lat/long of each point on a way.|
|addr:street||Used if it is not obvious where the access to the water point is from.|
|Specifying water point type|
|amenity||Identifies this feature as one which can provide drinking water||water_point|
|man_made||A range of water point types. Mutually exclusive to natural=*||water_well
|content||Used in conjunction with man_made=storage_tank||water|
|natural||A range of water point types. Mutually exclusive to man_made=*||spring|
|water||Used in conjunction with natural=water||pond|
|pump||Explains whether there is a pump or not. More information on the pump can be given by specifying whether it is powered or manual||yes|
|pump:type||This describes the model of the pump. There are several different manual ones, so this could be quite useful.|
|pump:fuel||I’m not sure about this, but I’d like to find a way to specify what fuel a pump uses, if it’s not manual.||diesel
|depth||The depth of a borehole or well, in metres (Note, this would require a redefining of this tag - it is currently only used offshore)||[Number]|
|Ownership, access & fees|
|name||The regular name of the pump||[Text String]|
|ref||A reference name of the pump (perhaps some form of code, see Tanzanian rural waterpoint database for an example)||[Text String]|
|access||Used to describe the legal access||yes
|fee||Used for specifying whether a fee is usually charged for a service, or for access||yes
|charge||Used for specifying how much is charged for use/access to a facility||[Text string]|
|operator||Used to name an entity who is directly in charge of the current object||[Text string]|
|operator:type||Used to specify the kind of entity the operator is||private
|opening_hours||Specifies when the water point is available. There are rules regarding format|
|start_date||This is when the pump was constructed||Year|
|intermittent||Used to describe whether the water point is always open||yes
|operational_status||Used to describe the current state of the water point||open
|pump:working||Explains whether the pump is of operable quality||yes
|indoor||Is the pump inside or outside? May be useful in built-up areas.||yes
|sufficient_quantity||Is there enough water to satisfy demand?||yes
|condition||The condition of the water point, rather than the quality of the water contained therein||good
|water_purification||Whether water purification is applied/available||yes
|drinking_water||Is the water of drinking water quality?||yes
|[Covered]||Specifies whether the water point is open to the elements or covered. However, covered=yes shouldn’t be used for underground elements.||yes
|Project & contact details|
|project||This is the name of the project.||[Text String]|
|source||This is where the information came from. If it’s from a project on the ground, then it should be survey, not the name of the project.||survey|
|note||Extra information||[Text String]|
Questions to answer
- Should completely private water points be put on the map as an amenity? If they are private, they are not a community service/amenity.
- Should more address keys be included?
Review of Water Point Tagging in southern Africa
All 3441 points with amenity=drinking_water in Africa below 1°S were surveyed. 165 different keys were identified:
- 3 were present for 100% of features
- 6 were present for 20–80% of features
- 18 were present for 5–20% of features
- 37 were present for 1–5% of features
- 101 were present for <1% of features
The values attributed to these keys were studied and they were categorised into 52 groups according to function.
This is a preliminary survey of water points to try and develop a method to survey all the tags on water & sanitation points across the developing world.
The aim of this survey is to understand the requirements of HOT/OSM contributors when they add WASH facilities. This can then be used to develop a clear and useful tagging scheme which will cover most information which they may wish to enter.
This is only a preliminary survey and so covers only one tag (amenity=drinking_water) across a smaller region of the world. It covers sub-Saharan Africa from the Tanzanian Northern border (1.0°S) to the tip of South Africa, including Madagascar.
A quick survey of the OSM wiki to identify common water point tags was performed. Those chosen for research were:
- man_made=storage_tank AND content=water
Due to there being so many water points in the region chosen, only features with the tag amenity=drinking_water were properly assessed. There were 3441 of these, and between them they had 156 different keys. An Overpass Turbo map of their distribution is shown on this page.
The features were extracted as a geoJSON, converted to an Excel file using an online conversion tool ready for analysis. The results are shown below in tabular form, followed by a discussion.
Table of Key Frequencies
This table shows the number of times each key was used across the 3441 water points.
Table of tag categories
This table shows keys which seem to convey very similar information, and are therefore suggested as being thought of as one category of information when developing a tagging procedure.
|'Correct' key||Alternatives in the survey||Total frequency|
|amenity (alternative tags)||water_point
|[Water & Point Quality]||water_quality
|content [of a storage tank]||6|
Discussion of major keys with many alternatives
All points in this survey had the tag amenity=drinking_water, but many also had very similar tags which provided the same information. 18 alternative keys, with 1989 entries, were identified. This suggests that a comprehensive but useful tag describing the water point is required. Many values of the tags described a water tap, a water tank or a water tower, suggesting that people wished to provide more information about the type of water source beyond the fact that it could be drunk.
Note that, once other water point tags are surveyed (man_made=water_well, water_point=yes, drinking_water=*, etc.) more thought may be required to ensure that the new tagging procedure is comprehensive and covers their needs too.
8 of the alternatives are from one project, but give similar information to one another. Another project has 3 very similar ones. A clear tagging strategy in a WASH methodology could help projects such as these to efficiently capture and manipulate their data.
This is another popular tag, with 1288 instances of tagging across 10 keys. An interesting point with the alternative tags here is that 5 of the 9 alternatives are from one particular project, but seem to give very similar information. This suggests that there is a need for an access tag which can take a range of values.
This tag had 15 alternatives, with 1165 instances of them being tagged. This is a critical tag for WATSAN projects and a suitable range of values could bring clarity to water point data. However, there is often the need to provide more information so a secondary category such as operational_status:note may allow for this to be accommodated.
Several of the six alternatives to this had an owner-style tag, rather than operator. I think it can be assumed for most water points that the operator, rather than the owner, is the important piece of information. There were 926 instances of these seven tags being used.
913 instances of this type of information were recorded across 7 keys. Values were a mixture of numbers and text strings, including currencies as well as costs per unit of water bought. It may be necessary to include two keys here, one which specifies whether there is a fee or not, and another with a text string where, for example, ‘7 KSh per 20L’ can be entered.
A mixture of ‘note’, ‘NOTE’, ‘notes’, ‘description’ and other tags were used 467 times across the points surveyed. The key ‘description’ is meant to be used to convey information to end users whereas notes are mainly meant to be read by other mappers. The conveyance of information kept within the ‘description’-style tags should ideally be able to be contained within the tagging protocol that is developed, and this tag can be avoided in the protocol.
There are quite a few keys which convey information about the amount of water available, or the number of people who use the water point. This is important to include within the protocol, and it may be split in two to produce better systematic values. There were 249 instances across 5 keys.
There are 104 instances of information about the project to which the water point belongs, across 5 keys. This is also important information, especially for finding your water points on the map using overpass turbo or a similar method. However, it is probably not necessary to have a separate key for each project, simply a value. It may also be sensible to include a project:date key to specify when the project was performed.
Several water points were given addr: keys, like a building. Information about what settlement the water points are in should be clear from the map, but addr:street may be useful in built-up areas where the route to access the point may not be clear.