Water RO System vs Gravity Purifier

RO (Reverse Osmosis) Water vs Gravity Water Purifier Selection Guide

Water is a precious natural resource, which is very important for the survival of all living beings, flora and fauna on this planet called Earth.

Even the 70% content of the human body is made up of water.

But this natural resource is depleting, and at a very fast pace. And the most common reasons for this are :

  • Inefficient use of water for agricultural practices
  • Overexploitation of groundwater resources
  • Sewage and drainage disposal in freshwater resources
  • Lack of efficient water management system
  • And of course, people’s careless state of mind and unawareness

In rural areas, where the water distress is high due to one or many of the aforesaid reasons, there are growing concerns about water-borne diseases such as:

  • Cholera
  • Diarrhea
  • Typhoid
  • Filariasis

In such a condition, it is very important to have access to clean and safe drinking water to ensure good health and metabolism of our body.

And for most of us, the answer to this question lies in RO i.e. Reverse Osmosis system, that is either installed or should be installed in our homes.

Before proceeding further, let me explain what is Osmosis and what is Reverse Osmosis?

Osmosis And Reverse Osmosis (RO)

Osmosis is a naturally occurring process that happens in plants as well as our human body. In osmosis, a weaker saline solution will tend to migrate to a strong saline solution, when separated by a semi-permeable membrane.

Now Reverse Osmosis is completely opposite to this. since we want to do something opposite to its natural process, we would need a pump to do that.

So basically, a RO system forces the high salt concentrated water i.e. tap water or raw water that we feed into the RO system, through a semi-permeable membrane, or filters that are installed in its way, to filter out all the impurities in it, and provide us with clean filtered water that is safe for drinking.

Do We Really Need It?

I will try to answer this question by citing a practical example.

How do we decide if we actually need a RO system for our drinking water requirements?

Just because our relatives or friends are using it or because we can easily afford it or it is a social status symbol now or the taste of water is not good.

The decision should not be based on anything else, but the TDS content of the water in your area.

What is Water TDS?

TDS (Total Dissolved Solids) in water are some minerals and ions present in the water. While some are beneficial for our body, excess need to be removed.

Drinking Water Tds Chart

TDS Level in parts per million (ppm) Water Quality
Between 50-150 Excellent for drinking
150-250 Good
250-300 Fair
300-500 Poor
Above 1200 Unacceptable

Water TDS can be checked using a TDS meter and the decision should be based upon the TDS content of the water in your area.

Please remember, that a TDS value up to 300 is acceptable.

If the TDS value in your area is high, yes you should install a RO system.

But if the TDS value is less than 300, you should not.

Because there are disadvantages of using RO system also. Let me explain :

  • RO system rejects a lot of water.

The lower the TDS of the RO water, the higher the amount of RO waste water it will produce.

Let me share my personal experience. When I installed the RO system at my home, it was rejecting a hell lot of water, 3 times water was rejected for  1 unit of drinkable safe water.

But, was it really drinkable and safe?

When I checked the RO water TDS, it was 20 PPM.

Remember, a TDS value of less than 50 PPM is dangerous for bones and health.

Immediately I asked the service person to increase to TDS value to more than 250 PPM but less than 300 PPM. Now the water is safe to drink and it also rejects very low water comparatively.

  • RO system rejects minerals that are necessary for our body.

This is also related to the concept I shared above. The lower the TDS, the more minerals will be rejected in the wastewater.

There are many variants of RO water purifiers available in the market in various price ranges. While buying, one should always ensure if a TDS controller is provided in the RO or not. ROs in the higher price range are usually equipped with a TDS controller which makes it easy for the installation person to adjust it as per requirement.

If it is not provided in the RO system installed at one’s home, it can be externally installed also by the service person.

Basically, TDS controllers work on a delta i.e. difference between the TDS value of input water and output water that we are taking from it.

Suppose in city X, the supply water TDS is 1000 mg/l. So the service person adjusted it to 200 mg/l as per customer requirement. Now, if that RO system is used in city Y where the TDS of the supply water is 1500 mg/l, the TDS of the RO system output water will no longer be 200 mg/l. Instead, it will be increased now due to an increase in the supply of water TDS or vice versa.

So it is always recommended to check water TDS at regular intervals or when relocated to a different place.

In such cases, having a TDS controller and a TDS meter makes this task very easy and affordable too.

How to check Water TDS at home

There are many digital TDS water meters available in the market which can be used to check the TDS of water. While buying, you should check its certification and cost also.

RO installation as well as membrane replacement should be decided on the basis of TDS levels in the water.

You can refer to this video also for a detailed guide for TDS water checking and setting its value.

RO Reject Water or Waste Water Uses

Water is really a scarce natural resource nowadays and we should not waste it. We should try to use it wherever possible.

While big industries use RO water waste in their own way, we, at home, can also contribute to this by using RO waste in some of the below-mentioned applications :

  1. Housekeeping
  2. Gardening
  3. Clothes washing
  4. Toilet cleaning

The list is not exhaustive and varies from person to person.

Price of RO Water Purifier

Ro water purifiers are available in the market at various price ranges, and it varies from product manufacturers to various filtration methods it employs. You may find KENT RO water purifier offering various products in the high price range of 15000 INR, but some other companies such as Aquaguard may be offering somewhat similar products at a comparatively lower price range of around 7000 INR. So it is at the user’s discretion which product he is comfortable with.

Popular RO Water Purifiers Available in the Market

  • Kent
  • Aquaguard
  • BlueStar
  • Aqua fresh
  • A.O. Smith
  • Eureka Forbes
  • Pureit
  • Tatacliq
  • Whirlpool
  • Panasonic
  • Havells
  • LG
  • Kara
  • Mi
  • and many more other options

Should I buy a Local RO Water Purifier?

That is a very common question that comes to mind of everyone who plans to buy an RO water purifier for his home use and came across various local options available in the market.

While local products are usually much cheaper than branded ones, people usually lack the wisdom or know-how in selecting the right product for themselves.

Obviously, branded RO purifiers are comparatively costlier due to the quality as well as the life of the filter membranes, plastic body, and other features (including an on-site service warranty) offered. If you do not indulge yourself in the chemistry of water filtration and can easily afford to pay a little higher, should obviously go for branded products available.

However, if you want to save money or couldn’t afford to pay high prices, then choosing a good local product would be the best option for you. But make sure, the product you buy should have a TDS controller, good storage capacity, and also comes with an on-site service warranty. Not only that, you may need to check water TDS at regular intervals to ensure membrane effectiveness.

Gravity-Based Water Purifiers

Now, what if the supply of water TDS in your area is good, but the water color or taste is not good.

There could be a variety of reasons for that. In such cases, Gravity-based water purifiers should be installed. There are many options available in the market.

A gravity-based water purifier runs without electricity and the speed of filtration depends upon the dust content in the water. If the dust content in water is high, it will take more time to filter.

RO (Reverse Osmosis) Water Filter

Basically, it consists of three filters :

  1. Sediment Filter
  2. Activated carbon filter
  3. UF membrane

For efficient use, these filters need timely replacement.   

These are comparatively cheaper than RO water purifiers.

Now, we decided what we have to buy, a Gravity-based purifier or an RO water purifier.

The next question that comes to our mind is which RO water purifier we should buy?

Well, there are many options available in the market to confuse any one of us. But our decision should be based upon the following factors :

  • Service and Installation cost

Usually, all RO suppliers provide installation and service up to a certain time limit, free of cost. But still, it is better to confirm once before buying a RO water purifier.

  • TDS controller

Now, this is something that is missing in most of the RO water purifiers available in the market. And people often do not ask or be told about this because they do not know why it is important.

Please refer to the example I shared above. If the TDS controller is not installed in the RO water purifier, you will not be able to adjust the TDS of the water, whenever required.

At that time, you have to spend extra money to get it installed and that may not be covered under the product warranty.

Always buy a RO water purifier with an inbuilt TDS controller.

  • Cost

The utmost important factor in buying anything from the market.  The cost may vary according to the RO water purifier storage capacity and other inbuilt support functions such as UV membrane, UF membrane, Alkalinity etc. The more services you ask for, the more you have to pay.

  • Annual maintenance cost

It is the annual cost incurred in the replacement of carbon filters and sediment filters of the RO water purifier. Normally, it is almost the same for our purifiers and varies according to the size of the membrane and filtration capacity.

UV Filter

This is not really a filter but a UV lamp that kills harmful bacteria and viruses in the water. It does not remove dissolved solids present in the water. Hence, it is always found after RO membrane as water needs to be relatively pure before being treated by UV.

Sediment Pre Filter

This is generally found outside the main RO unit in a separate encasement. It contains a microfilter or simply a micro spun (usually 5 microns) which removes sediments or dust particles. The time period could range from 3 months to 6 months depending on the quality of the water. It also increases the lifespan of the main membrane of the RO water purifier in India.

Activated Carbon Filter

An activated carbon filter purifies the water by removing chlorine and odor from water by trapping organic compounds and other substances.

Alkaline Water Filter

This new term “Alkaline” has brought many options for people to buy RO system.

This new product is being sold in the market as a healthier alternative to normal RO system as it not only reduces the TDS content, but also adds minerals to the water that are very important for the human body, which is usually filtered out in the normal RO system.

This product is particularly important and beneficial for those who suffer from joint problems.

A basic RO system not only reduces the TDS of the water but also reduces the pH of the water and makes it less than 7 (<7) thereby making it acidic in nature.

The alkaline RO water system increases this output water pH (between 7 and 10) by adding necessary minerals to the water and making it healthier for drinking.

The pH of the water can be easily checked using pH paper for pH solution. The recommended pH level of the drinking water is 7 or more than 7 (7-10).

If you are already using an Alkaline or copper membrane-based RO water system, then its pH should be checked at least once in six months. If the pH is less than 7, then the alkaline filter of the RO water system should be replaced. In the market, A-A or A-A-A alkaline water filters are commonly available.

Unlike, other RO filters and membranes, alkaline water filters are not uni-directional and water in -out pipes can be fixed over either side of the filter.

Final Words

I hope this article would help you in a practical way while buying a water purifier in an intelligent way and you will not only save water but also waste less.