How to buy Water Purifier Guide

What is turbidity in water

The meaning of turbid water is when the water appears cloudy or muddy with suspended solids in it. The solid particles in turbid water are so small that they do not settle down, but stay suspended in the water. Most of the time the suspended particles in water are colloidal, that means they are held in suspension in the water due to electro static repellent forces.

To measure the total suspended solids in water a measurement unit called TSS or Total Suspended Solid is used which is given in mg/L or milligrams total suspended solids in one litre of water. NTU and TSS are the standard units of measurement for water turbidity.

Water Turbidity NTU units

The universally accepted unit of measurement of turbidity in water is ‘NTU’, which is the abbreviation for 'Nephelometric Turbidity Units'.

NTU is a measurement of the scattered or reflected light through a sample of the water in an instrument called the Nephelometer. When there is more Suspended Solids or more turbidity, more light is scattered from the water sample and you get a higher value. So a higher NTU reading means that the water is more turbid. Most water standards like EPA and WHO set the allowable maximum value for NTU at about 0.1 NTU.

Total suspended solids in water

The total suspended solids definition is the weight of suspended solids in a unit volume of water, the weight is in milligrams and the unit volume is one litre. The total suspended solids method to calculate the TSS in mg/L is done in the laboratory by actually filtering the sample of water through special filter papers. The total suspended solids calculation is done by filtering a one litre sample of the water through a pre weighed special filter paper.

After the water has passed through the filter paper the filter paper is dried by incubating it at a pre-set temperature and a set time, as laid out by the standardised testing methods. The total suspended solids calculation is done by taking the difference in weight of the filter paper before and after it is dried to give the weight of the suspended solids in one litre and this gives the TSS of the water sample in milligrams / Litre or mg/L.


Water with a higher TSS in mg/L will obviously have a higher NTU reading, but there is no linear relationship between NTU and TSS. This is because the scattered reflected light reading in NTU is dependent on the size and shape of the particles in the water and there is no correlation with the weight of the suspended solids. So there is is no NTU TSS relationship.

How to clear up muddy well water

The earliest of water purification methods for turbid water or water with suspended solids was to pass the water through a piece of fine cloth or through a sand filter.

One of the most effective ways of removing turbidity in water is by precipitating the colloidal suspended mater in water using a flocculent like alum or Aluminium Sulphate. When turbid water is treated with a flocculent, the electrostatic repellent forces keeping the suspended solid as a colloid is neutralised and all the microscopic particles stick together or agglomerates to form large particle known as floc which settles down very quickly to the bottom. This is the method used by the large water purification plants, and the same method can be used to clear up muddy well waters. For personal use, turbid water is filtered through sediment filters which are explained on our page on sediment filters.

Best way to buy Water Purifiers in India

The best way to buy Water Purifiers in India is to first look at all models of Water Purifiers available online at the leading online Retailers in India. For example on the online webpage of All Water Purifiers available in India on, you will find the full range of Indian Water Purifiers complete with their best discounted price and full specifications. This is great information, and you can decide on which model of water purifier to buy. With the model of water purifier you want to buy finalised, you can go to local shops to try and find the model of water purifier you have chosen and see if you can get at similar price of that at In most cases the price from Amazon will be cheaper, because they buy in bulk from the manufacturers direct and they sell huge volumes because they are the world's largest and most trusted online retailer. If you buy from Amazon, they will arrange to have the water purifier installed in your house, usually free of charge.

Warranty and other facilities offered through Amazon are usually better than what you can get from local agents of water purifiers.

All pages in our website

Below are links to all the pages on this website and we hope you will make full use of all the great information about Indian Water Purifiers provided here.