Hawzah News Agency – The water of a well which springs forth from the earth, even though its quantity may be less than kurr(the amount of water which fills a container whose length, width and depth are three hand spans each), does not become najis(impure) owing to something najis falling in it, unless its color, smell, or taste changes.
However, it is recommended that in the event of certain najasah falling in it, a quantity of water should be drawn from the well. Details about this quantity have been elucidated in more detailed texts.
If najasah falls into a well and changes the smell, color or taste of its water, it will become tahir(clean) as soon as the change vanishes. The recommended precaution is to wait till it is mixed with the fresh water springing from the earth.