Proposed features/Fire Hydrant Extensions

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Fire Hydrant Tagging Extensions
Status: Draft (under way)
Proposed by: nfgusedautoparts
Applies to: Node
Definition: additional information for emergency=fire_hydrant
Drafted on: 2013-03-09

Some Extensions to support fire_hydrant


Some subtags in support of fire_hydrant are described. These tags contain detail about fire hydrants that have considerable value to First Responders. This proposal additionally proposes deprecating one value for fire_hydrant:type and adding two tags for fire_hydrant:type. Some new variations on fire_hydrant are included, as are new variations of colour. The meaning of colour as applied to fire_hydrants is formally defined, and additional colour subtags are proposed which cover common cases of hydrants painted in more than one colour.


Projects are in progress which aim to use OpenStreetMap to support First Responders. These tags are intended to support those projects by providing details about hydrants above and beyond those which are captured by the existing tagging scheme. Some of the data may be discerned from a physical survey of individual hydrants, and other data may be available from public databases. The most likely scenarios for First Responder use of OSM data are "mutual assistance" calls, where a responder travels outside their normal area of responsibility and as such knows less about local conditions than normal.


Wet Hydrants are generally fed by water mains in urban and suburban areas. The dimensions of the mains vary greatly, and so the flow capacity of the hydrants can vary substantially. The location of hydrants is the first requirement in a mutual assistance call; the second most important piece of information is the flow capacity. Some jurisdictions in the United States have adapted a colour scheme specified by the American Water Works Association. In these juridictions, flow capacity may be determined simply by examining the colour of the top and caps of a fire hydrant. In other cases, finding out the capacity may be more difficult.

Flow Capacities and AWWA Colour Scheme
Class Capacity Top & Caps Colour
AA more than 1500 Gps Light Blue
A between 1500 and 1000 Gps Green
B between 1000 and 500 Gps Yellow
C less than 500 Gps Red

Revisions to fire_hydrant:type

Fire_hydrant:type in its current form improperly conflates two concepts, the water supply and the physical delivery mechanism. I propose that type pond be deprecated, and three new values be added:

New values for fire_hydrant:type
Value Description
pipe delivery via a simple capped pipe. Most dry hydrants use this method
dry_barrel a style of pillar hydrant where the water shutoff valve is below ground, hopefully below the frost line. These are used on pressurized systems where freezing is a risk. They are occasionally used for dry hydrants when the water supply is higher in altitude than the hydrant.
wet_barrel a style of pillar hydrant where the barrel is pressurized at all times, with individual valves for each outlet. These are common in Southern California.

New Tagging

The proposed subtags for fire_hydrant apply to "wet" hydrants (e.g., pillar or underground). The colour tags apply to both wet and dry hydrants.
Proposed tags
Tag Description
fire_hydrant:class In the US, classification per American Waterworks Association. Valid values are AA, A, B, and C. If fire_hydrant:class is present, fire_hydrant:flow_capacity is redundant and should be omitted.
fire_hydrant:flow_capacity Minimum capacity (units are gps or lps (gallons per second or liters per second)). If fire_hydrant:class is present this is redundant.
fire_hydrant:water_source Source of water for hydrant. valid values include pond, stream and main.
in_service yes if the hydrant is in service, no if it is not. If omitted, a hydrant is presumed to be in service.
colour The colour of the hydrant. Unless otherwise specified, the entire hydrant is this colour.
colour:bonnet colour of the top section ("bonnet" of the fire hydrant if different from the colour tag value. Blue, green, yellow and red are the valid values in the AWWA scheme, but many jurisdictions do other things.
colour:cap colour of the caps of the fire hydrant if different from the colour tag value. Blue, green, yellow and red are the valid values in the AWWA scheme, but many jurisdictions do other things. If caps are painted in more than one colour, list all colours separated by semicolons.
colour:reflective color of reflective material, if any (commonly stripes or bands around the barrel.)