[Guite]

We have been told by the Kent technician that the efficiency of an RO system in removing TDS is 90%. Which means it passes through 10% TDS. Is this true? I thought it would have been 100%.

In our area raw water TDS is 1700 . So by above statement if we shut off the TDS controller in the Kent RO, we will still get TDS of 170 (ppm?). What option do I have to reduce the TDS further? What is the ideal TDS level for human consumption?

[Mortis]

Originally Posted by Guite

We have been told by the Kent technician that the efficiency of an RO system in removing TDS is 90%. Which means it passes through 10% TDS. Is this true? I thought it would have been 100%.

In our area raw water TDS is 1700 . So by above statement if we shut off the TDS controller in the Kent RO, we will still get TDS of 170 (ppm?). What option do I have to reduce the TDS further? What is the ideal TDS level for human consumption?

A TDS of below 200 is perfectly fine for consumption. As long as the filter is removing pollutants and killing germs its alright. Some dissolved salts in water area actually good for us, you dont want to consume water that is TOO pure also.

If you want to reduce the TDS further, you can look for pre or post filters with water softening beads or Ion exchange resins. ebay.in is a good option for this.

[distiller]

Hi All! My Aquasure RO has gone kaput. Also my service experience here in Bangalore has been very poor.
Has anyone experience of using AO Smith RO water purifier, if yes how is the performance & how is the service experience.
Any recommendations for a good purifier.
Thanks in advance!

[Sebring]

Just moved to Kent from Eureka Forbes, and really happy with the water quality. Service is better I feel. Stopped buying Bisleri water cans completely, something which we used to do as a habit.

[distiller]

Hi All! To update, installed Zero B's Eco RO model. Had evaluated AO Smith & Zero B. But the latter was very quick with the sales call, follow up, order processing & installation.
Will keep you all posted, once I log in some litres (miles)

[enzo10]

Originally Posted by DwarkaDelhiWala

All Kent ROs mix pre-RO membrane water with that of post-RO membrane filtered water to little bit raise the TDS - and they call it "TDS-Controller ". Then what is point of having a RO membrane at all?

Hi All,

If we take the example of Kent - Pearl, a portion of inlet water is diverted before the RO filter and is moved via UF to TDS controller. Technically speaking UF can filter out viruses, but the pores are bigger to let the salts pass. Further the combined (RO + UF) water flows via UV before reaching the tap.

Therefore my query: Is this setup harmful or does it reduce the effectiveness of the purifier?

thanks

[sgiitk]

Originally Posted by distiller

Hi All! My Aquasure RO has gone kaput. Also my service experience here in Bangalore has been very poor.
Has anyone experience of using AO Smith RO water purifier, if yes how is the performance & how is the service experience.
Any recommendations for a good purifier.
Thanks in advance!

One of the best in terms of product and quality are ZeroB. They are an old firm Ion Exchange India. They are better known in the industrial world. Only they use an Iodine based polisher and not Ultraviolet. However, they claim to polish out the Iodine in an additional stage.

However, in terms of service inquire locally. almost all buyers of water purifiers use local service agents.
.

[Aroy]

If TDS is high, it is better to install a basic TDS filter ahead of an RO system. The advantages are
. Based on the TDS levels you can size the pre filter up, not possible in an RO System
. The filter cartridge of a basic filter is much less expensive than the one in RO system.
. Pre filter will prolong the life of RO filters

In fact most industrial systems use a series of TDS filters before processing water further.

[RajaTaurus]

I have been following this thread for some time and I thought I would clarify few basic things here regarding Reverse Osmosis process.

TDS: Total Dissolved Solids. TSS: Total Suspended Solids.

Filtration:
All kind of pre filtration systems including sand filters, cartridge filters and UF can only 'filter' Suspended Solids. Purpose of pre filtration is only to safe guard the RO Membrane from physical fouling. In industrial systems, there are coagulation//flocculation which consolidates suspended organic/ inorganic matter and then multi-media filters which removes these matter. In household systems, no chemicals are used and only physical filtration is used.

Reverse Osomosis:
RO membrane actually does not 'filter' the water, but it 'permeates' pure water through the membrane while 'rejecting' all other constituents of water, which goes as 'reject'. This is where the dissolved salts gets 'stopped' from passing through and we get clean water on the other side of the membrane.
Any level of pre filtration does not reduce TDS, but it only helps reduce TSS.

Recovery: This is the ratio of Volume of output water to Volume of input water. This does not control the quality of the output water i.e. TDS.

Rejection: This is the ratio of TDS of Output water to the TDS of Input water. This is the measure of the quality of the output water.

As per WHO, a TDS of 500 is recommended as safe drinking water. But IS:10500 clearly specifies safe limit for each element. In some plants we have to maintain the output TDS as low as 150 in order to get some elements under safe limit.

So, basic guideline is,
1. Test your raw water for all constituents based on IS:10500.
2. Decide on pre filtration based on TSS.
3. Decide on RO system based on TDS.
4. Decide on post treatment if required.

While selecting household RO systems, testing input water can help a lot in deciding the required filtration system. Post treatment is generally not deployed in household systems.

If the input water does not contain any contaminants like fluoride or arsenic it is no problem to mix raw water with Permeate to get required TDS and taste.

There is absolutely no problem or health hazard to drink reverse osmosis output water, though the TDS is low. With Indian food habits, we do not require the basic elements from water to supplement out daily requirement. Only thing is the taste, but then bottled water too have a TDS of 40 and we have become used to its 'taste'.

Please post any questions regarding RO and I will be glad to answer.

Me - Ex-Technical Director of India's largest SWRO Plant at Chennai.

[Thad E Ginathom]

Originally Posted by RajaTaurus

Please post any questions regarding RO and I will be glad to answer.

Me - Ex-Technical Director of India's largest SWRO Plant at Chennai.

Wow

Please feel free to write an entire series of posts on water purification. We have the advantage of other experts in their fields doing so on Team-BHP. Many of us would appreciate further and deeper (but layman-accessible) information on this one.

Maybe you could start a new thread in the assembly line? Oh, I guess I'm asking you to write a book! No obligation, of course!

[RajaTaurus]

New thread? A book? In this world of Googlization, I don't think there is any need for all that. I can help with specific queries regarding water treatment.
A quick warning: Chlorine is killer for RO membrane. If you have RO system with Metro water as input and if there is any smell of Chlorine in water, please do not use the RO until the smell is gone.

[Thad E Ginathom]

Interesting point. We do not get to smell the water before it goes through the RO unit. Actually, we do not, at this time, get Metro water, although it is supposed to be on its way.

Had a vague idea that some of these activated-charcoal filters remove chlorine?

When I was in UK, I was a strictly-tap-water man, with no time for fancy filters and certainly none for buying bottled water. But I did try out a portable system (bought for a trip to India; it clogged up in a week) on my tap water, expecting it to do nothing, but was surprised at the difference in smell and taste.

[RajaTaurus]

Actually, if the metro water has excessive Chlorine, you would get the smell even from running tap in wash basin or shower. That is when caution is required. I have experienced this while I was in Chennai many times.
Activated carbon filter is a good option in this regard.
In UK, the tap water would contain minerals prescribed by Health department (or relevant regulation) and that RO would have removed those salts. That could be the reason for difference in taste and smell.

[sandeepmohan]

Originally Posted by sudev

AFAIK ultrafiltration is next step RO. However could be wrong.
So this unit does not have any reject water stream?

http://permionics.com/pureflo/products.html

Ultrafiltration has been around even before RO was widely available in India.

The unit does have a water reject system but to be done once in 24 hours and not while filtering. It is a manual system. You basically flush the system. It is around a liter of water you let out before you start using it. Needs no power.

Over and above the other complaints, it is not built very well too if you were to compare with the competition. The only saving grace is that it does not require any attention other than changing the membrane pads once a year or based on the water impurity level.

[rdst_1]

Hi guys,
I have a Borewell which supplies water for our household and drinking purposes. Last year, we had the water tested and it was fit for consumption, which I was expecting. However, we still use a Tata Swachh MF membrane unit to remove any sediments and germs. Now I am in need to setup a similar gravity based unit which should be able to handle large amounts of water. Main consideration is towards removing of sediments.
Basically, I need the whole water supply of the house to pass through a basic filtration system which should at least remove all the sediments as they seem to be clogging up our pipes despite us waiting for the sediments to settle down. I wouldn't mind if the whole setup also includes a germ killing solution and an MF membrane as well just like our Tata Swachh. The water will be utilized by our animals as well so am looking to provide a clean water solution for them as well.
Around 2000L of water will be needed to be filtered every day. I have been told before to buy reusable sediment filters of industrial standards for the sediments. Is something similar available in the germ kill and MF membrane options as well.