How to purify bore well water for drinking?
How to get well water tested in India, water quality testing labs in India
The only way you can how to tell if well water is good or bad is by getting the well water tested in one of the water quality testing labs in India. There are many water quality testing labs in India where you can get well water analysed. This Government of India Website has a List of water testing labs in India,You can submit the sample to our lab , you need to take a sample of the well water for testing to them.
Well water test results explained
After testing the well water, the water testing lab will issue a water analysis report or water test result certificate in a standard format as per the Indian Water standards. The water test results will show all the possible harmful contaminants listed and the actual value of contaminant present in the well or bore well water sample. Against the actual value of contaminants present in the well water sample will also be given the acceptable maximum limit of that contaminant according to the Indian water standards or in according to the WHO guideline water standards. A well water analysis report would look something like what is shown in our page on How to buy a water purifier
How to make well water safe for drinking
Depending on the water test results of the well or borewell water, these are the steps on how to clean well water for drinking and make the well water drinkable.
Well water safe with no problems
If you are lucky with your bore or well water and the well water test results proves that the well water is safe and does not have any contaminants above the maximum contaminant level or MCL as recommended by the Indian or WHO Water Standards, then all you need to do is to have a simple cartridge filter like the ones explained and also to remove any odours and to improve the taste of water install also an Activated Carbon filter as explained in our page on Activated Carbon filter.
How to remove Arsenic from borewell or well water
If the test results show that there is Arsenic or other heavy metal poisoning of the well or borwell water, then the best way to purify well water will be to use a Reverse Osmosis or RO purifier unit. There are other methods to remove Arsenic from well water but RO is the most practical and reliable way to get rid of Arsenic from water.
Arsenic is a major problem of borewell water in many parts of the world. Since Arsenic salts in well water has no smell or taste, you will not know about the presence of Arsenic in water unless the water is tested. So testing for Arsenic is imperative when using well water for drinking. Drinking water with Arsenic can cause severe damage to health. Arsenic poisoning is cumulative, that means any water Arsenic that gets into your body is not removed, but stays in the body and accumulates. As you continue to drink the Arsenic water, you are being slowly poisoned and with time it will cause severe health problems and early death.
Arsenic and other heavy metals in well water is one of the most dangerous aspects of drinking well water. So you should have a fail safe water purifier system for Arsenic by installing a Point of Use - POE RO water purifier in the kitchen where water for drinking and cooking is taken. The POE RO should be in addition to the whole house well water purification system against Arsenic in the well water.
Arsenic can be removed by oxidation with chlorine (Sodium Hypochlorite) or potassium permanganate or coagulation with ferric chloride and then filtering it. Activated alumina and ion exchange resins are also effective. The best option to purify Arsenic well water is by installing an RO plant for the whole house water supply.
Smelly well water problems
Sometimes borewell water smells like rotten eggs due to the ground water being contaminated by sulphur compounds or 'sulfur bacteria' which causes Hydrogen Sulphide H2S gas to form in the well water. H2S or Hydrogen Sulphide in well water in very low concentrations can produce very bad rotten egg smell in water. In open wells it could be due to rotting organic matter and the solution here is to try and clean open well by pumping out some of the water to reduce the water level in the well and then going down into the well and physicaly cleaning the well by getting rid of any organic matter and then adding chlorine bleach.
Shallow wells are more likely to have the problem of rotten egg smells and the solution is to have a deeper well.
Aeration is a good option for low concentrations of hydrogen sulfide in well water since the Oxygen in air reacts with hydrogen sulphide to convert it into an odorless Sulfate. Manganese greensand filters being used for iron removal is also quite effective in oxidizing and converting H2S into an oderless Sulphate. If all this fails due to high concentration of hydrogen sulphide, then continuous chlorination with a dosing pump of a solution of Sodium Hypochlorite or Calcium Hypochlorite will be required. Chlorine oxidises H2S to odourless Sulphate. Chlorine dosing also gets rid of Arsenic and heavy metals in well water and could be your one source answer on how to remove heavy metals from water. After the chlorination dosing you need to add an activated carbon filter to remove excess chlorine. Expert guidance from a water treatment specialist company would be required for this.
Muddy well water problems
The best way to purify dirty or muddy well water is to put a solution of Alum (Aluminium Sulphate) into the well directly in case of open well or into the primary holding tank into which the borewell water is pumped into. Alum is safe and is a flocculent used by almost all public water authorities for primary settlement of sediment in water their water purification. You do not need to use too much. As a rough guide dissolve about 50 grams of Alum in about 5 to 10 liters of water in a bucket and pour it evenly over the surface of the well or the bore well holding tank. 50 grams of Alum is more than sufficient for a well of upto about 6 meters (20 feet) diameter. For very small wells and holding tanks use about half the quantity. The water should become clear within 24 hours with almost all the mud and dirt settling to the bottom of the well or tank. In case your water has no other contaminants other than turbidity which was caused by the dirt and muddy water, then before using the water run it through a simple cartridge filter like the ones explained on our page on Sediment filters and also to remove any odours and to improve the taste of water install also an Activated Carbon filter as explained in our page on Activated Carbon filter.
Iron in well water problems
Iron removal from bore well water is important because Iron in water is a very common problem due to the fact that iron is found almost everywhere on the earth's surface. Iron salts in water can be removed in several ways most of which involves the oxidation of the iron salts in water so that it becomes insoluble and precipitates out of the water, after which it is filtered out. Several methods of oxidation of iron in water are there like aeration of well water, chlorination of whole well water and ozonation. The most common method of removing iron from borewell water is by using oxidising media filters for iron like Manganese Greensand and Pyrolusite or a catalysing media like BIRM. It is also possible to treat well water for the removal of iron by Ion Exchange media, though this is not the recommended treatment for home well water purification systems.
If the major problem in borewell water is iron, then the best solution is to go for either a Manganese Greensand or BIRM treatment of the well water. Regenerating Manganese Greensand with potassium permanganate is not that difficult and can be done by the house owner without much difficulty. BIRM treatment of well water iron requires no regeneration but needs air to be introduce into the well water by simple aeration methods like venturi action before entering the BIRM media. You will need to consult an expert in water treatment to decide on the best treatment for well water with high iron content.
Whole house water purification system for well or borewell water
Whole house well or borewell water purification system with an RO plant is the best solution for all well water problems like Arsenic, Bacteria, iron, bad smell, heavy metals, etc. A Reverse Osmosis Purifier Plant or a Nanofiltration plant will get rid of all known impurities of well water.
To calculate the capacity of the whole house water purification system for well water with a Reverse Osmosis water purifier plant, it should be assumed that the average daily need of water per person is 200 liters. So for example, a family of 6 will need 6x200=1200 liters of purified water per day from the RO water purifier plant. RO purifier plants are usually classified as having a flow of so many Liters per Day or LPD of purified water.
Since the reject water of an RO plant is clean highly filtered water with a higher TDS, it can be used to flush toilets, cleaning floors, watering plants and so on. The product RO purified water should be used only for drinking, cooking, bathing, etc. So you should have separate tanks for RO purified water and RO reject water. The house piping should be so arranged that all the water going to the toilet flushes should come from the overhead tank for RO reject water. One separate tap should be there in each bathroom and outside the kitchen connected to the RO reject water tank. Water from this pipe will be used for washing floors and such work where you will not require purified low TDS RO product water.
The reject water of an RO purifier has already undergone fine filtration and has been disinfected to protect the RO membranes and this was done before the whole raw water to the RO was pumped under high pressure to the RO membrane. From this purified raw water pure water goes through the membranes into the purified water tank and the reject water flows out the reject water tank. The reject water from the RO water purifier will have higher salt content due to rejection by the RO membrane.
If it is assumed that 20% of the pure water required by a household is used in flushing toilets and washing floors, then you could get away with a smaller whole house RO plant. In our example above a 1000 liters per day RO purifier plant would do the job.
For cleaning, initially you could use the RO reject water and final rinses with the RO permeate pure water. This is because the reject water of the RO contains a lot of salts, and when the water dries, these salts would leave a scale, a whitish colored stain marks on the cleaned surface. You avoid this by a final flush with the pure permeate water.