How do you prevent nitrate contamination?

How do you prevent nitrate contamination?
Prevention of nitrate contamination of the water supply is critical. Wells need to be isolated from possible sources of contamination and to be protected from surface damage. Abandoned wells need to be sealed to prevent contamination. Sinkholes are direct routes to groundwater and should never be used as garbage dumps. Good nitrogen management is needed when applying fertilizers, both on the farm and in the home yard and garden.

The surest way to deal with a contaminated water supply is to find a new, clean water supply. If you do not have access to a new water supply, the contaminated water can be treated to remove the nitrate.

How can nitrate be reduced or removed from water?
Nitrate is a very soluble substance, easily dissolved in water and extremely hard to remove. Treatment for nitrate is, therefore, very complicated and expensive. However, only water used for drinking and cooking needs to be treated. The three methods of reducing or removing nitrate are: 1) demineralization by distillation or reverse osmosis; 2) ion exchange; and 3) blending.
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When to Test?

Indian Portable Water Testing Kits

How accurate is the above kit? Any feedback from users?