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Demineralizing Plant for a Residential Project: Some Queries, Mumbai

My client is erecting a 50 stories building with LEED platinum rating in  central Mumbai, and we are planning a Demineralizing plant to minimize the reject. Since Demineralizing plant normally are used within the pharmaceutical industry, there's not much information about Demineralizing for residential potable use and therefore the following questions.


1) What type of Demineralizing plant can be used for potable use?

2) Which regulations are recommendable to follow for acid storage?

3) Brief calculations shows that we'll have around 1 ton of acid to be stored and injected into the purified water to re-establish an appropriate mineral content for drinking purpose. What guidelines to follow for the handling, storage & disposal of example acid next to the plant? We have tried to scan EPA but without luck.

4) Do you agree that a Demineralizing plant is an environmental and economic solution for water treatment for residential use?

Thanking you for your expertise and time,

Lars Kjeldsen

Director, Advanced Infrastructure and Environment





A few questions, we need to know the source of water and the use of water after DM plant.( is it municipal water or sewage)

DM Plants are an operational and environmental hazard for commercial and institutional operations.

Lot of info available with us w.r.t to green buildings.

You could contact on


Dear Sir,

Assuming the 50 story building is a residential building, a more appropriate approach to dealing with water management issues for the campus would have the following elements to achieve both economic and ecological soundness :

a) Identify the water sources (piped, ground etc) and arrive at quality and quantity sustainability issues for the sources.

b) Actively integrate Catchment management and Rainwater harvesting into
the design to ensure atleast supplemental source of water and ground water recharge.

c) Design Waste water treatment and plumbing systems such that low value uses (eg: gardening and flush) can be taken care of recycled wastewater.

d) Ensure a water distribution system to households of the complex in a way that water used by each household is metered and measured. If the water sources are completely private for the supply, understand production cost of water and arrive at a water tariff regime that households will pay that will reflect the production cost of the water, incentivises responsible usage and penalises wastefulness.

e) Ensure installation of water efficient end use devices like part flush.

Consider water treatment (such as demineralisation) within this overall framework of water management. Often treatment technologies are opted for when not necessary. Treatment technologies are not in themselves economic or environmental solutions but are tools within a larger approach to ecological and economic water management.

Demineralisation in-fact is rarely used in the domestic context. Depending on the quality of source water treatment necessary can vary from nothing to Reverse Osmosis (with simple Rapid sand filter, on-line chlorinator/disinfection in the middle).


Avinash Krishnamurthy
Biome Environmental Solutions Pvt Ltd / Rainwater Club


The 2004 WHO study by F. Kozisek( and several other groups have found that drinking demineralised water and also the RO, distilled or softened water that is devoid of essential minerals such as Ca, Mg, etc. has several ill effect on human health. Such water is ion-hungry, very corrosive and removes essential minerals from human body.

Optimum levels of Ca should be 20-30 mg/L, Mg should be 40-80 mg/L and TDS should be 150-200 mg/L. Nitrates should be lower than 10 mg/L ideally, though WHO limit is 45 mg/L. The latter breeds dengue mosquitoes in warm region of India.

Undisturbed natural ecosystems have capability to produce mountain springwater that has the ideal mineral water quality, in Himalayas and Nilgiris, for example. Only these are allowed to be packed and termed as 'mineral water'. All other bottles have 'packaged purified drinking water' that follows commonly agreed parameters that can be achieved practically, such as IS 14543:2004.



Dr Uday Bhawalkar
Director R&D
Bhawalkar Ecological Research Institute (BERI), Pune


Dear Lars Kjeldsen,

The learned member Mr. Avinash in his response has dealt with most points on holistic water management indicating the need for RWH, WWT processed water for reuse for flushing and irrigating gardens and recovery of manure from sewage Etc.

Multiple water-supply pipelines to have potable water separate from toilet flush water and others. And also have multiple waste-water lines sewage from toilets and the other line to cater to discharges other than sewage, Etc.

It is indicated by you that for your potable and for swimming pool water supply etc.. you are installing a DM plant on your raw water supply circuit , so that your drinking water plant- RO plant or any others would have less reject , is it??, and that the DM plant would use 1000kg of how much time??..this will itself have a lot of pollution Etc. Pl do indicate your views on this.

We are appreciative that your project is approaching for LEED rating.. And more thought should go into minimizing the impacts on pollution, and conserving natural resources and energy and installing less power consuming initiatives.

You can have On-site composting of bio-wastes- ex. Horticulture/ greens, urine diversion with harvesting urine for manure, use of solar-thermal water-heaters, landscaping with appropriate plantation at out-doors and with indoor air-quality improvers Etc. on roof-tops, terraces could be introduced .

Our Ngo works on these initiatives and pl. feel free to be in touch for any specific details.

With well wishes from VigyanVijay,

Er.Ajit Seshadri
The Vigyan Vijay Foundation,


Er. Ajit Seshadri,Head- Environment, The Vigyan Vijay Foundation


Dear Mr.Kjeldsen,

Demineralised water is not really suitable for potable use.Demineralistion removes most of the minerals present in the water,and water for potable purposes must have some minerals present. Demineralisation involves the use of Hydrochloric/Sulphuric acid and caustic soda to regenerate the plant and you are left with waste water that is much worse than the reject from an Reverse Osmosis(RO) plant.

The quantity of waste water produced by each regeneration depends on the quality of feed water used and can sometimes be as much as the reject from an RO plant.What is worse is that it is likely to be highly alkaline and needs to be neutralised before further treatment.

If you want an expert opinion, provide me with the analysis report of the water that you propose to treat and use for potable purposes and I will tell you what would be the best method of treatment.




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