Article Last Updated: January 2023
Demineralised water is water that doesn’t have any ions, minerals, nutrients – nothing.
Demineralised water is water completely (or at least to a ridiculously high degree) free of dissolved minerals as a result of one or more of the following processes:
- Membrane filtration (e.g. nanofiltration or reverse osmosis).
What is Demineralization?
Demineralization is a water purification process that works by removing mineral salts from water through ion exchange.
What is Demineralised Water How Is It Obtained?
Demineralised water is free from all soluble mineral salts. It does not contain any anions or cations.
Demineralised water is what you get when you pass water successively through an anion exchange (in the OH– form) resin and a cation exchange (in the H+ form).
The Meaning of Demineralised Water
Demineralized water is a water purification process that leaves you with very pure water.
Demineralized water and deionized water are generally considered to be different from distilled water. Distilled water is water purified by boiling and recondensing, a process that also eliminates salt ions.However, the main differences are that demineralized water is usually more free of mineral ions.
This depends on the amount of processes used for it.
And distilled water may contain less organic pollutants, because the deionization of uncharged molecules like viruses or the bacteria.
Also, deionization leaves less “scale” than distillation and is also a cleaner production.
Demineralised Water Plant?
Demineralised water plants are power plants (large heavy plumbing machinery) that filter water leaving you with pure water.
This is typically used for a large factory, industrial building or premise that has a very large need for water filtration.
A demineralised water plant consists of two pressure vessels containing cationic and anionic exchange resins.
Various types of ion exchange resins can be used for the cation and anion process. This depends on the nature of the impurities in the water and what the final water is used for.
VERY Technical description of the demineralised water plant process:
Typically, the cationic resin works in the hydrogen cycle. The cations in the water (i.e. calcium, magnesium and sodium) pass through the cation exchange resin.
This is where they chemically exchange by hydrogen ions.
The water passes through the anion exchange resin where the anions (i.e. sulfate, chloride, nitrate and bicarbonate) chemically exchange by hydroxide ions.
The water that emerges from this process consists essentially of hydrogen ions and hydroxide ions. Which is the chemical composition of pure water.
A simplified demineralization plant process can consist of a:
- Composite resin container with strong cationic charge and anionic resin.
- Control panel, which measures conductivity and alarms, etc.
- Installation of acidic and caustic injections of containers in bulk or bottles.
What Are Demineralised Water Plants For?
The ultra pure water of a demineralized plant is typically used to:
Feed high pressure boilers.
Wash water for the manufacture of computer chips.
Medical facilities or technical laboratories that need very pure water.
Used for pharmaceutical process water.
Microelectronics and any other process that requires high purity water.
The type of resins used and selected for demineralization plants depend on many factors. This includes things like:
- Water temperatures.
- The level of treated water quality required.
- Input water quality or issues with the input water quality.
- Presence of organic foulants.
- Flow through plant required.
- Regeneration method – either counter-current or co-current regeneration.
Demineralised Water pH
Demineralised water pH is 7.0.
But note that if you leave demineralised water in the open air for a few hours it will dissolve carbon dioxide.
It will do this from the carbon dioxide in the air. This will make it become slightly acidic with a pH of 6 or so.
Fresh deionised water is truly neutral with a pH of 7.0.
How to Make Demineralised Water
To get real demineralised water you need a treatment plant or machine. However it is possible to make distilled water at home and distilled water is very close to demineralised water in composition.
Distilled water is a very easy thing to do. There are many different methods that you can use and you can even do it at home.
In very simple terms, you create distilled water when you remove chemicals and minerals from water.
People make distilled water for a variety of uses, including drinking, filling humidifiers, watering plants, steam irons and even aquariums and so on.
- You will need 2 glass bottles. This process works best when at least one of the bottle arches outward from the neck and prevents the distilled water from slipping back into the other bottle.
- Fill 1 bottle with tap water. Finish the filling about 12 inches from the top.
- Connect the 2 bottles in the neck and secure them firmly with tape.
- Use a 5 gallon stainless steel saucepan with boiling water to distill the water.
- Tilt the bottles at an angle of about 30 degrees and tilt the empty top bottle into the edge of the pot. The angle facilitates the collection of evaporated distilled water.
- Place an ice pack on the bottle. This creates a cold / heat barrier, which leads to the evaporation of water in the cooler bottle.
- Continue with the distillation process until you have collected enough distilled water in the bottle for your needs.
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Where To Buy Demineralised Water
It is easy to find and buy demineralised water online at places like Amazon.
You may also be able to find it at certain health food stores but best to buy online.
This is because most places are unlikely to have this type of water in stock.
Another option is to buy a machine that can create demineralised or distilled water for you.
This will save you money in the long run and stop lots of waste from plastic bottles going to the landfill site.