Talk:Tag:waterway=drain

Clasification

There is a problem with the drain classification. It is useful to distinguish between a natural river and artificial drainage channel but mapnik assumes that a drain is narrow which is wrong. For example the South Forty Foot Drain in the Fens is, surprise, surprise, 40' wide. I am about to change the Cut Off Drain near Mildenhall to river as it will then be rendered at an appropriate width. Malcolm Boura 21:39, 5 June 2008 (UTC)

A lot of drains - including many in the Fens *are* very narrow - possibly even narrow enough to jump over. The large drains - the Forty Foot Drain, the Hundred Foot Washes etc. - are more like canals than most drains. I think the waterway=drain tag is probably designed for drainage ditches - e.g. see here, rather than something like this. Richard B 23:49, 5 June 2008 (UTC)

This is essentially a rendering bug. The renderer should use the width=* property of each feature to determine how many pixels to use at each zoom level. (If the width is not stated explicitly, then the renderer should use the default width for the type of feature; the default widths should be documented). --T99 22:57, 1 September 2012 (BST)

drain vs. ditch

How do I decide between the two? The pictures and descriptions look very similar.

In my usage, drains are typically lined with concrete or rocks, while ditches are dug in bare ground. Drains also have a marked direction of flow and can be quite steep (I tag dam spillways as drains); ditches could be level. --T99 22:57, 1 September 2012 (BST)

There is now waterway=spillway for spillways. I've never seen a ditch that is used to carry water (i.e. not solely as a barrier) and completely level. How would that even work? It would eventually fill up and overflow whenever rainfalls continue.

See the comment I just made at Talk:Tag:waterway=ditch#ditch_vs._drain for why I think the distinction of ditch vs. drain should not based on the material. I suggest an intuitive usage of the two tags: Drainage of ground water => waterway=drain, just surface water => waterway=ditch. If the bottom and the walls are made of concrete, it actually can't be used for drainage because that material is impermeable. Tag it as ditch or canal instead. --Fkv (talk) 05:19, 11 August 2022 (UTC)

Drain holes?

How should one tag a drain hole where storm water flows from a street surface into an underground drain but the route of the drain cannot be determined? --T99 22:57, 1 September 2012 (BST)

manhole=drain fits. Add hole:diameter=2 or similar if it's something huge. Alv 11:41, 3 September 2012 (BST)

Should it be manhole? Not all drain inlets are large enough for a person, and commonly (around here) they are separate from the actual manhole. I suggest something more like inlet=drain would fit better. Fearsyth (talk) 03:52, 21 October 2019 (UTC)

This is a good point. Please see discussion about outfall which aren't designed to let man go through as well Fanfouer (talk) 22:21, 23 October 2019 (UTC)

Suggest a new tag waterway=drainhole which would only apply to nodes. An alternative could be to use waterway=drain (node), which again would only be used on a node. --Courtland.yockey (talk) 17:41, 8 May 2021 (UTC)

This is currently drafted on Proposed_features/Inlets_proposal, mainly with inlet=*. Feel free to propose new values Fanfouer (talk) 18:23, 8 May 2021 (UTC)

Direction

As I see this page included in Category:Way Direction Dependent category, should I assume that the way must be draw so that the direction of the way is downstream?. If so is it better to add, as in page Tag:waterway=stream, the following sentence?

Direction of the way should be downstream.

AnyFile (talk) 15:14, 11 March 2013 (UTC)

Added (copied from [[Tag:waterway=stream], with some modification). Also added some other clarification (from the same source). -- AnyFile (talk) 17:03, 26 November 2016 (UTC)

Being more precise in definition

I would like to remove the a stream that has been channelised part of the definition. This does not commonly represent current mapping practice and makes the tag overlap a lot with waterway=stream. Depending on how you define channelised the vast majority of flatland streams in strongly industrialized regions like central Europe would fall under this. Any objections?--Imagico (talk) 16:55, 17 November 2016 (UTC)

Good idea --geozeisig (talk) 06:59, 18 November 2016 (UTC)

Add incompatibility with usage=*

Currently, drain is defined as a waterway carrying useless water. Then, should we explictly state that waterway=drain is incompatible with usage=*?
waterway=drain + usage=* would mean it's an actual waterway=canal. Fanfouer (talk) 10:55, 29 May 2019 (UTC)

I just checked how often drains are tagged with usage=irrigation today. It looks like there are only 8 waterway=drain with usage=irrigation. However there are other ways of tagging this: the older tag service=irrigation is used 1069 times with waterway=drain, and the even older tag irrigation=yes is used with it 221 times.

By comparison, there are 3605 waterway=ditch tagged as tagged as used for irrigation: https://overpass-turbo.eu/s/JqW

And there are 10687 ways tagged waterway=canal and one of the irrigation tags: https://overpass-turbo.eu/s/JqX

This suggests that tagging the waterway=drain with usage=irrigation is rare, and not a standard tagging system. This makes sense based on the plain-language meaning of "drain" in English, which suggests removing unwanted water rather than providing water for irrigation. --Jeisenbe (talk) 12:03, 29 May 2019 (UTC)