Water Treatment in times of Water Scarcity – Need for better operation and maintenance of Water Treatment Plants in your Housing Society

History of Growth of Water Treatment Industry

The water treatment industry in India is well established and has been around since the early 1950s with just a few players  at that time, several of them subsidiaries of companies known internationally. The market grew over the last 5 decades and today, there are probably close to a few thousand companies(including many small, local companies) as  players now in the market. As the industrialization and development of the country progressed, water use too grew rapidly with water  being used with utter profligacy depleting ground water and polluting surface water with industrial waste water and enormous quantities of domestic sewage.

As water quality deteriorated, there was a clear opportunity for companies to bring in Reverse Osmosis (RO) technology to cater to the drinking water needs of the country. The standard for drinking water BIS-10500 had also been established in 1991 by the Indian Standards Institution (ISI) now re-named Bureau of Indian Standards (BIS). This standard reflected the deterioration that water quality had undergone, particularly ground water. BIS-10500 has laid down the desirable quality, the acceptable quality and lastly the permissible quality for water used for human consumption if no better,  alternate source was available. Such a situation was ideal for the growth of the water treatment industry to cater to the domestic segment using RO for drinking water purification since ground water over much of the country had deteriorated due to over exploitation leading to water with dissolved solids content far in excess of the maximum limit specified by BIS-10500.There was enormous growth in the industry that catered to the water demand of the domestic market.

The economic reforms of 1991 too saw the accelerated GDP growth. In this  scenario, the real estate development industry too geared up to meet the pent up demand for housing in the country. If one takes Bangalore as a typical example of this growth, it saw the city of Bangalore growing in size, spreading out, growing in all directions with a virtual forest of apartment complexes and gated communities springing up in almost no time at all! As much of this growth was in areas to which BWSSB was unable to supply Cauvery Water, the residents of such areas had to make do with ground water which was mostly hard water and had excess total dissolved solids. Now, this gave birth to Water Treatment Plants in Apartment Complexes and Housing Societies.

Water treatment plants in Apartment Complexes & Housing Societies

Let us first examine in detail the reasons leading to Water Treatment Plants in Housing Societies.

Hard Water

High hardness in water causes deposit of scales in vessels used for heating water,in hot water geysers and in pressure cookers. Hard water causes poor quality of washing in washing machines, increases consumption of detergent and prevents soap from lathering when having a bath or even when just washing utensils. Hard water prevents dal and rice from cooking, spoils the taste of tea when it is used to make tea and, it also ruins the taste of whiskey when it is used to make a drink!! Hard water fails to  quench your thirst when you drink it. Hard water also forms scales in the pipes carrying water and can warrant replacement of all water pipes in the complex after few years which can be a very huge expense.

Obviously, softeners are the answers to such problems. Softeners have therefore become very common in apartment complexes  in the form of a large centrally installed system that softens all water used in the premises it is installed in. Some times there is no centralized softener in an apartment complex and one finds that some individual apartments have installed small domestic softeners to soften the water for various uses or to soften the water fed to a small domestic RO unit.

Total Dissolved Solids (TDS)

Total dissolved solids is the total of all the minerals present in a water including the total hardness. A total dissolved solids content of approximately 300 to 500 ppm (or mg/litre) is acceptable and does not need to be treated by an RO unit.  However, in most places well waters often have TDS levels as high as 1000 ppm or more.

This is where an RO system comes in as very useful as it can remove 90 to 95% of the TDS and thus provide good tasting water.  Using an RO unit would produce treated water with TDS as low as 20 to 30 ppm. However, it is important to note that hard water cannot be directly fed into a RO unit as it forms hardness sacale on the RO Membrane. Thus, Soft water is the best kind of water to feed an RO unit. There are apartment complexes where the residents of a complex have shared the cost of installing a central RO system which is used to supply RO water to all the apartments in the  complex 

Suspended Impurities

In a majority of the cases, softeners need to protected from the presence of suspended impurities in the feed water. This is done by installing a pressure sand filter and, some times by also installing an additional activated carbon filter which protects the softener from the effects of chlorinated water and organic impurities. Such filtration systems are also a must as a pre-treatment for RO systems.

Thus, essentailly we need water to pass through filternation plats, followed by softener, and then through RO Unit to get potable water.

Swimming pool purification process

In apartments / socieites where Swimming Pools are present, swimming pool purification plants need to be present to take care of the clarity of pool water and need to be used  well in advance to ‘turn over’ the entire contents of the pool before swimmers can use it. Pools need water that is clear, have an almost neutral pH and are free from  any bacteria. This involves having to dose a variety of chemicals into the pool water daily. This ends up increasing the chemical content of the pool water which then needs to brought down by diluting the pool with fresh water after the pool filter has been backwashed(cleaned). The backwashing process reduces the quantity of pool water and this is made up with fresh water to dilute the concentration of chemicals in the water.

Now comes the question – with every step of water treamtment, there is bound to be waste water getting generated. How much is this quantity and can anything be done about this ‘waste’ water.

Waste Water Generated by each treatment process

In such a scenario, it is absolutely essential to take a good look at the waste water generated by each treatment process which are given below:

  1. Filters: Water lost due to backwash to clean filters is between 10 to 15%. This means that for every 100 litres of filtered water, a filter needs 110 to 115 litres of feed water. This applies to swimming pool filters too.
  2. Softeners: Water lost due to ‘regeneration’ or ‘ recharge’ is as much as 30% if inlet hardness is around 300 to 350 ppm as CaCo3 and increases as the inlet hardness increases. Feed water needed will be 130 litres or more for each 100 litres of  soft water or more depending on higher hardness values.
  3. RO plants: Small, domestic units used in individual households are the most wasteful and the waste can be as high as 90% in small units and lower if the RO system is of large capacity and waste in such systems would be around 50 to 30% of feed water.

Need to Reduce Waste Water from the Purification/treatment methods

Hardly any housing society or apartment residents’ association or its plant operating personnel know or bother to monitor the waste water that is created by any of the treatment systems used in an apartment complex. Worse still I have yet to see any plant installed which has a water meter fitted at the inlet that can help to monitor the amount of water treated and wasted during regeneration of softeners, backwash of filters and during normal operations of RO systems which have a steady flow of ‘ reject’ water going to waste during operation. In a majority of the places they do not even have an accurate figure of the total water coming into the property particularly if they have yielding bore wells. As most parts of Bangalore now have dry bore wells and get water in tankers, some vague figure based on the number of tankers supplied is available. Tanker volumes are notoriously unreliable and they seldom supply what they claim as the tanker capacity.

Need to have better operations and maintenance of WTPs

I have seen numerous WTPs (filters,softeners, RO plants & swimming pool purifica-tion).Most of them ( close to 95%) are badly operated or not operated. Maintenance is seldom done as per schedule(actually, I have yet to see a maintenance schedule!). This is a wasteful practice and results in the unnecessary waste of water that could otherwise have been used in some apartments.

Proper treatment of waste water

Regeneration/reject waste and filtration waste waters in any property usually goes as a mixture clandestinely to storm water drains. The quality of this waste water is such that pollution control laws do not permit such disposal and it would normally have to be sent to the STP for treatment, as, normally STP treated water is usually re-cycled and not (can not be) discharged.

Bleak future

If this is the state of affairs with WTPs, I question the need to even install such systems as they do not meet the objective of producing treated water. The main point that needs to be kept in mind is that the increasing scarcity of fresh water will make the use of WTPs unviable as there will not be enough fresh water (from bore wells/tankers) for both use and regeneration/re-charge of WTPs. I also predict that swimming pools will soon become unviable for swimming pool use, but could definitely be used as a storage whenever a sizeable volume of water becomes available.

About the author
S S RanganathanMr. S.S. Ranganathan, author of this guest post, is a retired senior executive of Ion Exchange and currently a freelance Water Management Consultant based in Bangalore. His blog at “India Water Portal” explains the work he does in detail. He can be reached at +91-93437-34229.

This article aims at providing information for benefit of ApnaComplex customers and blog readers. The thoughts and opinions expressed here are solely of Mr. S. S. Ranganathan and NOT of ApnaComplex or its representatives. We suggest to post your queries or comments below and Mr. Rangathan can answer them at his convenience.
  1. A very well written article. Water Scarcity is one of the major issues in our country and should be handled properly. Thanks for such a wonderful post.