Water hardness & Special treatment

Introduction Water described as "hard" is high in dissolved minerals, specifically calcium and magnesium. Hard water is not a health risk, but a nuisance because of mineral buildup on fixtures and poor soap and/or detergent performance.

Water hardness One of the factors that establishes the quality of a water supply is its degree of hardness. Hardness is defined as calcium and magnesium ion content.

HARDNESS OF WATER: Hardness may be defined as a soap destroying power of water. It is temporary when there is presence of calcium bicarbonate and magnesium bicarbonate & permanent when it is containing calcium sulphate chlorides and nitrates.

Water hardness Water hardness is usually noticed because of difficulty in lathering soap and the formation of a scum in the bathtub. Ca and Mg form insoluble salts with soaps causing precipitation of the soap scum.

What is soft water? Soft water produces a rich lather with ordinary soap. The pure rain water, spring water, etc is soft is soft water, since it contains less amount of dissolved salts in it.

Cause of water hardness Most hardness is caused by carbonate mineral deposits, hardness is usually reported as parts per million (ppm) of calcium carbonate (by weight). A water supply with a hardness of 100 ppm contains the equivalent of 100 g of CaCO3 in 1 million g of water or 0.1 g in 1 L of water .

Effects of water hardness Hard water interferes with almost every cleaning task from laundering and dishwashing to bathing and personal grooming. Clothes laundered in hard water may look dingy and feel harsh and scratchy. Dishes and glasses may be spotted when dry. There is soap wastage.

Effects on body Hair feels dry and sticky Hair is resistant to color Dandruff or eczema of the scalp Dry, flaky skin Thinning hair Colors fading too quickly Perms appear to fall out Discoloration or darkening of hair Hair lacks body and shine

Effects of water hardness Another effect of hard water is “boiler scale”. When hard water comes into contact with dissolved carbonates, a precipitate of insoluble calcium carbonate forms. This “scale” can build up on the inside of water pipes to such a degree that the pipes become almost completely blocked.

Types of hardness Hard water is of two types based on the types of salts dissolved in it:- Temporary hard water: - Contains Calcium and Magnesium Bicarbonates. Permanent hard water: - Contains Calcium and Magnesium Chlorides and Sulphates.

Removal of hardness of water Temporary hardness can be removed by boiling the water and then filtering it. The Calcium and magnesium bicarbonates present in temporarily hard water form insoluble precipitates on boiling the water. The Carbon dioxide present in bicarbonates is also removed during boiling. Ca(HCO3)2 → CaCO3↓ + CO2 + H2O. In this reaction, CaCO3 is the insoluble precipitate which can be filtered out. CO2 gas is evolved, and soft H2O is left behind

Permanent hardness Permanent hardness can be removed by addition of washing soda (Na2CO3) in water. Reaction: Na2CO3 + CaSO4 (this is present in hard water) → CaCO3↓ + Na2SO4 In the above reaction, the dissolved salt CaSO4 reacts with washing soda to form a precipitate and evolve Carbon dioxide (CO2). The insoluble precipitate CaCO3 is easily removed by filtering.

Other methods: By addition of , -lime, -sodium carbonate - permuted (which is a complex compound of sodium, aluminium and silica.

Fluoridation of Water Deficiency of fluorine in drinking water is associated with dental caries, and excess with dental and skeletal flouorosis. The term fluoridation has been given to the process of supplementing the natural fluoride content of potable water to the point of optimum concentration.

Defluoridation In some geographic areas, water may contain a high level of fluoride. Water is defluoridated by phosphate to reduce fluorides to optimum levels

Selection of source of water In selecting a source attention must be given to possible future developments that may influence the continued suitability of the source. Other consideration include: Quantity Quality Protection Feasibility Treatability

Swimming Pool Sanitation Swimming pool water is exposed to: Feacal contamination Organisms from skin and nasoharynx

Sanitation Measures 2.2 sq. m. is required per swimmer. All swimmers are directed to empty bladder and use the toilet before swimming. A cleansing shower bath should be taken. Filtration of water Chlorination A continuous maintenance of 1 mg/liter of free chlorine residual provides adequate protection.