# Salt water fire drops

**URL:** <https://boards.straightdope.com/t/salt-water-fire-drops/423784>\
**Category:** Factual Questions\
**Created:** [October 24, 2007, 2:43am UTC](https://boards.straightdope.com/t/salt-water-fire-drops/423784 "2007-10-24T02:43:04Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Mangosteen](https://avatars.discourse-cdn.com/v4/letter/m/6a8cbe/32.png) [@Mangosteen](https://boards.straightdope.com/u/Mangosteen)\
**Post date:** [October 24, 2007, 2:43am UTC](https://boards.straightdope.com/t/salt-water-fire-drops/423784/1 "2007-10-24T02:43:04Z")

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Are the planes and helicopters using ocean water to extinguish the fires along the coast in California?

If so, won’t the salt make it difficult for plants to grow in those areas in the future?

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**Author:** ![Una\_Persson](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/una_persson/32/346_2.png) [@Una\_Persson](https://boards.straightdope.com/u/Una_Persson)\
**Post date:** [October 24, 2007, 3:45am UTC](https://boards.straightdope.com/t/salt-water-fire-drops/423784/2 "2007-10-24T03:45:40Z")

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[QUOTE=Mangosteen]  
Are the planes and helicopters using ocean water to extinguish the fires along the coast in California?

If so, won’t the salt make it difficult for plants to grow in those areas in the future?  
[/QUOTE]

Not likely. There won’t be nearly enough salt deposited from the limited application of salt water in a couple of air drops. A few rains will almost certainly dilute the salt to the point of being a non-issue.

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**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\
**Post date:** [October 24, 2007, 4:20am UTC](https://boards.straightdope.com/t/salt-water-fire-drops/423784/3 "2007-10-24T04:20:14Z")

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According to this Australian PDF, [Air Operations Manager](http://rfs.nsw.gov.au/file_system/attachments/State/Attachment_20050526_6596D579.pdf), salt water is a problem for the aircraft:

> [@](#):
>
> Salt water can be used for helicopter operations but most aircraft operators are reluctant to unless absolutely necessary, due to the corrosive effects on aircraft engine and airframe components. Chiefly it is the ingested spray from the rotor wash that causes the corrosion.

Many aircraft use a mixture of fresh water, Ammonium sulfate/phosphate (up to 240 mM if I’m reading [this patent](http://www.patentstorm.us/patents/6162375-description.html) correctly), and guar gum to put out fires.  
Ammonium sulfate/phosphate isn’t nearly as corrosive as NaCl, plus it’s a good _fertilizer_.

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**Author:** ![St.Urho](https://avatars.discourse-cdn.com/v4/letter/s/8e7dd6/32.png) [@St.Urho](https://boards.straightdope.com/u/St.Urho)\
**Post date:** [October 24, 2007, 5:10pm UTC](https://boards.straightdope.com/t/salt-water-fire-drops/423784/4 "2007-10-24T17:10:02Z")

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What’s being dropped will depend on what sort of aircraft is doing the dropping. Fixed wing aircraft will generally drop slurry, and will be reloaded at a tanker base. Rotor wing aircraft generally drop plain water, which can be obtained from rivers, lakes, or specialized tanks.

St. Urho  
wildland firefighter