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Hard water treatment plant- maintenance

The community in which I live buys bore well water which is hard; the same is treated for hardness using three stage filtration units -

  • Sand bed filter
  • Activated carbon filter unit
  • Resin filter unit.

We use about 1 lakh liters per day; inspite of regular back washing and re-generation using salt etc, the sand filter unit recently failed; the sand became solidified and had to be replaced.

Now we understand that since the unit is in operation for 2 years, both the activated carbon and resin have to be replenished/replaced.

  • Is there a scientific way to know when these replenishment/replacement have to be done?
  • How does one know if the back washing is done effectively?
  • Is measuring the hardness pre and post treatment the only test to assess how effective the water treatment is?
  • What purpose the meters (measuring pressure we understand) in each of the filter unit serve?

We shall greatly appreciate if some one educate us on these aspects. Thanks very much in advance!



1. Correct operation & maintenance of your WTP

Dear Ecomate,

On reading your query,it becomes quite clear that your plant comprising sand and activated carbon filters followed by a water softener is not being operated correctly.Virtually all such plants I have seen in apartment complexes/gated communities are like yours, not correctly operated,in fact they are maloperated! Now, the answers to your questions:

  • The scientific way to find out when the media in the filters and softeners needs to be replaced is to first of all get a professional, well trained and educated team of operators.Such a team would maintain a log book of all data from the plant such as how much water has been softened between two regenerations for softeners,when were the two filters backwashed and for what duration and also  at what pressure drop across the filter beds was it done.After backwashing correctly, the pressure drop across the filter beds should be practically nil.When the pressure drop goes to 5psi or more,it is time to backwash.

             Samples of resin and media need to be sent to special laboratories to test and the test report would specify if the media needs changing.

  • Backwashing can be considered considered effective if the pressure drop across the filter bed is nil. In the case of both types of filter, correct backwash will bring out turbid water and backwash needs to stopped when the water comes out clear.
  • Yes,if you have a softener,unless you monitor the hardness in treated water, there is no way of knowing when it is exhausted and needs to be regenerated for the next cycle of operation.
  • The 'meters' you refer to are actually pressure gauges.One at the inlet of each filter/softener as well as at the outlet.These indicate what is the differential pressure across the media/filter/resin bed of each unit.If the differential pressure is 5psi or more, backwash is required.

In my experience, it is very rarely that an apartment complexes' association hires a professional operation and maintenance agency because of the cost involved.They generally hire 'labour' with no education or training simply because it is cheaper to do so.The downside is that they end up spending on replacing media and resin which will wipe out all the so called 'savings' due to untrained labour.

If you want help in this matter and to help you find professionally trained operation and maintenance staff, you are welcome to contact me.



2. professional operation and maintenance agency

Hello Mr Ranganathan

We are having similar plant as mentioned by Ecomate & we are struggling t manage it, since we have not got any professional to manage it.

Can you please let me know the professional operation and maintenance agency whom we can contact in this regard ?




3. Professional O & M of WTPs

Dear Mr.Krishna,

I can put you in touch with a professional agency,but, I need some information on the plant first.Can you get in touch with me on 9343734229?




4. Response

Dear Ecomate,
Mr. SS. Ranganathan has already explained very aptly and clearly regarding the issue. I just want to add my bit to bring more info. regarding O&M of Softener unit

You have mentioned the community has installed three filter units on their water line for treatment of water.
1. Sand bed Filter
2. Activated carbon filter
3. Resin Filter unit ( This I believe, is Softener Plant)
Functions of these units are as follows :
a) Sand filter is for removing suspended particles, dirt etc.
b) Activated carbon filter is for removing colour and odour
c) Softener plant is for removing hardness from water
First two units need periodical backwash to clear clogging created in it by suspended particles and dirt etc. Pressure meters installed on line indicate extent of clogging.

In case of Softener unit, as the hard water is passed through it, its resin removes hardness from water and produces soft water . Slowly and progressively the resin's capacity to remove hardness is reduced and finally exhausted after certain amount of water is passed through it. After the capacity of resin is exhausted, only hard water ( in your case borewell water, as it is ) comes out of softener. At this stage the resin  needs to be regenerated by passing sodium chloride salt solution to recharge the resin in the softner.

The time cycle for exhaution of resin capacity will depend mainly on three factors a) Size of softener (quantity of resin in softener) b) Quantity of water passed through softener every day and c) Total hatdness of source (borewell) water.

Normally borewell water has high water hardness. Also, from the quantity of water that, you have mentioned, you are using (one lakh litres per day), I believe, the hardness of softener out-put water might be shooting up in one or two days only. At this stage you need to regenerate the resin in softner to recharge it to its original power. After this, in case the resin regeneration is not done, we are just passing the water through softener, without softener doing any work, since its capacity is exhausted. Installation of softener has no meaning after this period unless regeneration is done.
You have not mentioned how often you carry out testing of water hardness and regeneration of resin. For knowing when to do the resin, you have to test the hardness of softener out-put water periodically ( say once in 4-8 hours ) depending on quantity of water passed. When the hardness value more than required  is noticed in softener out-put water line, you need to start regeneration

Simple Hardness Testing Kits are available in market ( Prerana Laboratories also manufactures such kits). Hardness can be monitored by a layman by using these kits.
Prerana Laboratories also manufactures ONLINE HARDNESS MONITOR, which automatically analyzes hardness in softener out-put water line contineously and gives audio-visual signal, which alerts you regarding need for regeneration of softener, when hardness in the line crosses the set limit. Using this signal, with aditional arrangements, the Monitor can start automatic regeneration of the softener also to make the operation fully automatic, if necessary.Incidently, ONLINE HARDNESS MONITOR is first of its kind in India

You may please refer my article in EA WATER magazine ( Jan 2011 issue) for detailed discussion on softener functioning and its monitoring.
Coming back to the issue of changing the resin in yuor softener, you need not change resin immediately without checking the need for change. Please monitor the functioning of your softener by testing hardness in out-put water line. In case your resin is giving satisfactory quantity of  out-put water, then there is no need to change the resin, right now. If you change the resin arbitarily, without monitoring its output per cycle etc regularly., same story will repeat again after few days and change of resin will unnecessary expences and a waste.
Will be plesed to mail. copy of my above refered article and more details of our ONLINE HARDNESS MONITOR for your info. My mail ID is

Ravi Savant
Prerana Laboratories, Near Cjhhatrapati Bank, Vishal Nagar, Jagtap Dairy, Aundh-Wakad Road, Pune-411027. Tel: 9371015199

5. Water conditioner for 70 flat apartment


I am staying in a 70 flat apartment and since the water quality is not good (the TDS and hardness of water is very high, it is in the order of 800 ppm) we are planning to go in for a water conditioner.

Initially we thought of installing a water softener. However, since maintaining a water softener system is very cumbersome, one of the water treatment companies suggested water conditioner. We want to check the pros and cons with the experts before proceeding further.

The following information we got from the water treatment company.
The water conditioner consists of advance composite pressure vessel, nano resin catalyst and a 130 micron pre-filter.
These are things which he claimed that the conditioner would do:

  • Phase 1: The catalytic surface pulls the calcium and magnesium and converts these to nano crystal particles. These nano crystals are so small that they are 1 billionth of a meter: 100000 times smaller than a single strand of hair.
  • Phase 2: In this phase the existing scales in the piping is removed. The nano crystals formed during the previous phase are neutral and cannot attached to surfaces and due to their large surface area and nano structure they bind to calcium ions in the scale, gradually breaking the grid structure of the calcium scale deposits within the pipes.
  • Phase 3: A 3 to 5 micron protective corrosion layer is formed; this layer is formed as a result of nano crystals reaction to the pipes. As soon as the layer is formed it can no longer grow bigger, but it creates a complete protection.

Can anyone who is aware of such things guide us? Please tell us if this system really works.
Thank you

6. Please contact for inexpensive physical water conditioners

Please contact for very inexpensive physical water conditioners with 100 % free trial for a month.

Rates are very economical - ( 1" = 7000 ). We wish to spread this simple but effective conditioning technology. Business propogation is secondary.

93222 86745

7. Borewell water treatment for 3 unit house needed

We have a 3 unit apartment. The plot size is 1200 sq ft. We depend on borewell for water. Can you suggest a water treatment company who can install treatment unit for us.

Thanks and regards,

8. Water conditioner for bore well water


Read of your requirement. I would suggest that you use an electronic water conditioner which has the following features:
1. It is installed in the pipeline coming from your borewell pump. It is connected across the motor terminals such that it gets power supply only when the motor is switched-on.
2. It is a very low power consumption device (50W)
3. It requires no maintenance and is a fit-it and forget-it unit.

You will get the following benefits:
1. The system kills the bacteria and germs in the water, making the water potable.
2. It will blast the calcium crystals to dust particles. These particles will settle at the bottom of the overhead tank. Use a normal water filter (to block any dust particles in the water)
3. The water will give better foam when you use soap.
4. You will find no white stains on the taps or floors (which are caused by hard water)
5. You will be protected from hair loss and skin infections.
6. The plants in your garden will be healthier.

Please send me your e-mail id if you are interested.

9. Water Softner

Please get in touch at the mentioned e-mail ID

10. Need details of electronic water conditioner along with cost

Please, let me know the details of electronic water conditioner and approx cost.

My email id is singh.vivek.73 at

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