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Can you use deionised water in the cooling system?

Discussion in 'Motors' started by jsmoke, 18 Feb 2021.

  1. jsmoke

    Capodecina

    Joined: 17 Jun 2012

    Posts: 10,032

    I still cant find a definite answer. Can you use deionised or distilled water mixed with coolant in the cooling system?

    Some seem to say ok, others say don't do it?
     
  2. MrFunex

    Wise Guy

    Joined: 17 Oct 2005

    Posts: 1,128

    Location: Southampton

    I always have, with seemingly no ill effects. It’ll depend on the type (colour) of coolant you’re using.
     
  3. Zeeflyboy

    Wise Guy

    Joined: 21 Jan 2016

    Posts: 2,176

    All the typical PC water cooling coolants you can find are mostly distilled or deionised water mixed with various things like glycol and corrosion inhibitors, dyes etc.

    Distilled water would be best, but deionised is fine. You can run purely with water if you wish but you’ll need to maintain the loop a little more often as otherwise you may get biological growth. The main advantage of the various coolants over just water is added protection from corrosion and they usually contain biocides to help prevent fouling.

    If you are just topping up your loop a little then, assuming you are using a typical PC coolant, a little deionised or distilled water will have negligible impact on your coolant’s additive ratio. Add too much and you may make the biocides/corrosion inhibitors less effective and dilute any dyes but that’s all really.

    Edit, ignore all that rambling - I totally missed which sub forum this was!
     
    Last edited: 18 Feb 2021
  4. Jokester

    Don

    Joined: 7 Aug 2003

    Posts: 41,539

    Location: Aberdeenshire

    There's not a significant difference between distilled or de-ionised water, either way you really want to add corrosion inhibitor & biocide to it for long term piece of mind.
     
  5. theone8181

    Soldato

    Joined: 27 Mar 2013

    Posts: 5,077

    Isnt di water really bad if you've got any uncoated aluminium in there?
     
  6. Jokester

    Don

    Joined: 7 Aug 2003

    Posts: 41,539

    Location: Aberdeenshire

    So is distilled!
     
  7. tom_e

    Man of Honour

    Joined: 26 Dec 2003

    Posts: 27,587

    Location: Shropshire

    You lot might want to check which sub forum this was posted in :D
     
  8. Jokester

    Don

    Joined: 7 Aug 2003

    Posts: 41,539

    Location: Aberdeenshire

    Haha!

    The same principles apply though to car coolant - distilled or deionised, it's all the same.
     
  9. Zeeflyboy

    Wise Guy

    Joined: 21 Jan 2016

    Posts: 2,176

    pmsl, good shout... just saw it in new
     
  10. peterwalkley

    Mobster

    Joined: 23 Feb 2009

    Posts: 3,750

    Location: South Wirral

    If I overclock my car will it handle crysis at 1080p ? I'm sure someone down the pub was talking about clocking cars recently ...
     
  11. Dandle

    Mobster

    Joined: 4 Nov 2003

    Posts: 4,391

    Location: Ashford

    You can but you can also use tap water. The antifreeze is designed to be used with tap water and has the additives needed to stop things like galvanic corrosion and limescale. Depending on the car make there are different types of antifreeze though so make sure you use the right one so they don't react with each other.
     
  12. Scythe

    Soldato

    Joined: 23 Jun 2005

    Posts: 5,326

    You can on a temporarily basis. I wouldn’t advise it for any longer than a couple of months.

    coolant is cheap enough, if you just need a top up then you can usually by a litre bottle for a couple of £.
     
  13. Dandle

    Mobster

    Joined: 4 Nov 2003

    Posts: 4,391

    Location: Ashford

    I didn't mean straight water, I meant with anti freeze.
     
  14. Nasher

    Capodecina

    Joined: 22 Nov 2006

    Posts: 19,593

    I think DI water becomes slightly acidic over time. Tap water is stable.
     
    Last edited: 18 Feb 2021
  15. Doobedoo

    Mobster

    Joined: 24 Jul 2016

    Posts: 3,310

    Location: South West

    [​IMG]

    I can’t see it being an issue. Comma state on the bottle it’s suitable for the dilution of antifreeze.
     
  16. Dandle

    Mobster

    Joined: 4 Nov 2003

    Posts: 4,391

    Location: Ashford

    I didn't mean it would be an issue but its a waste of money. You can use tap water with antifreeze and there are no ill effects. Garages wont be putting deionised or distilled water in your car.
     
  17. Doobedoo

    Mobster

    Joined: 24 Jul 2016

    Posts: 3,310

    Location: South West

    Oh no defiantly I was just showing what is wrote on the side of my bottle.