Protect Household Steam Appliances De-ionised Water stops furring, limescale formation, residue, spots & stains on surfaces. Ideal for your car batteries & radiators, steam iron, steam generators, steam mops, wallpaper strippers, window cleaning, baby sterilisers, fish tanks, humidifiers. Proactive Car Maintenance Use deionised water to fill radiators & lead-acid batteries, & to dilute antifreeze for engine coolant. Deionised water is contaminant-free, so will help to stop corrosion & keep your car in perfect working order for longer. Boosts Car Detailing Improve surface adhesion by using deionised water before sealants, coatings & paint finishes. Save time on polishing & waxing by using a deionised water car wash first. Ideal to dilute clay cloth/bars, lubricants and windscreen washer fluids.