The cause of the bad smell depends upon what the water smell like.  It could be low (ppb) levels of hydrogen sulfide.  This would leave the water very clear but would smell bad to most people.  Other sources of bad smells would be things such as amines or organic sulfides.  So it sounds like you need to do a thorough water analysis that is capable of detecting these types of compounds.

Hi Hopewell,

Water that gives off a distinctive smell is most likely contaminated with hydrogen sulphide. Please check the following links and pdf attachments for the details.

http://www.water-research.net/index.php/sulfur

http://www.health.state.mn.us/divs/eh/wells/waterquality/hydrosulfide.html

http://www.extension.umn.edu/environment/housing-technology/moisture-management/why-water-smells-bad/

Best

Most of the times bacterial contamination is the cause. Presence of sewer lines or large waste dumping areas in near proximity can contaminate ground water very easily. It is much easy for ground water to get contaminated by bad waters if residential areas are near from your bore well or open well.  Bacteria produce H2S, Methane etc which imparts bad odors in water.

You can carry out simple H2S strip bacteriological tests suggested by WHO to know if there is presence of bacteria,

check the link, you may find such product locally. 

http://waterclues.com/products/h2s-vial-bacteriological-kit-pack-of-10

A geologist or groundwater hydrologist familiar with the geology and conditions may give you the reason for the bad smell, most likely as explained by the quality responses you have already.  Well drillers often take records of materials drilled through to obtain water sources, so this information, properly analyzed might have supported the assumption or given you added information.  Drinking or using groundwater for other domestic uses deserves a degree of testing.  I have attached a good document on drinking water from forests and grasslands, and since you did not suggest how deep the well is, portions of groundwater comes from recharge areas such as these areas, but filtered through layers of soils and varying degrees of connection to geologic materials, some of which dissolve and leave bad tastes, smells or even may once in a while include some hazardous or less than desireable content.  It is just good practice to have a competent well driller that has kept adequate records, and have the water tested, especially for a community water system, if there are any noticable changes in quality of water or health of people.  I have read that some of the healthiest water is milky glacial melt, so we probably cannot just look at the water and say it is drinkable.  But I also known a few hardy individuals during my life who drink without concern as they have apparently gotten used to the bad tasting sulphur water and stinky bath and wash water with no apparent effect beyond the odor, non-white clothes, etc.  If you live next to a paper mill or an animal feed lot, you eventually just get used to it.  You can probably find a listing of drinking water specifications through EPA in USA.  

Bad smell is usually associated with reduced compounds. Its origine can be, both, biological or geological.

In the case of a biological source, you must look for organic matter pollution around the aquifer.

But there are springs of sulfurous underground water associated to geological features, and most of the cases have been the origin of medicinal spas.

The solution implies some sort of treatment.

Hopewell,

I agree with the previous answers that hydrogen sulfide and organic sulfides cause rotten egg and sulfourous odors in groundwater. Groundwaters are low in O2 which results in reducing conditions and favors sulfate reducing bacteria that produce reduced sulfur compounds.

A few cautions are warranted.  First, the descriptors of the odors are the first step in identifying the odors.  If the odors are sulfur-like, then sulfur compounds ate likely implemented.  If the odors are urine-like, then ammonia, which also can occur in ground water, may be the cause of the odor.  The short OpFlow article describes sulfur odors in hot water heaters; similar microbiology applies to groundwaters although the anode/cathode chemistry are different.

Second, if bacteria are involved, then they can be in both the ground water and the storage tank.  Treating the ground water will control the odors, but they may re-occur if there is a long storage time in the tank.

Lastly, this is a common situation in both the developing and developed worlds.  If the water tastes or smells bad, even if it meets water quality standards, people avoid using it.  I attached papers on odor descriptors and causes of tastes and odors.

Mr. Hopewell Molefe 

Omnia Group, Protea Chemicals

Hydro- geology is an intricate subject. Water from ground aquifers are an excellent repositories of good usable water for the community. Sufficient care is to be taken to ensure that ground water is not contaminated or polluted.

In simple terms, we train the community sourcing ground water for their domestic-usage to resort to simple understanding on the qualities of water.

C-A-T-S are the main 4 basics for good water.                                                           C- stands for clean and clear.                                                                                      A- Alkalinity to be around 7.5,                                                                                     T- Tasty to mean that water has appropriate minerals, and salts aiding human growth. i.e chemical composition of salts contained din water- hard or soft etc,         S- indicates sterility of water not infected,

In order that the water is to be well maintained in the ground- aquifers ( sub-soil water- tanks ) care is taken that rain water, or run-off water from up-stream is led for recharge in a clean manner. Here it can be done with aided means or naturally it occurs.

Physically the recharge water  is led into rocks-soil profiles giving filteration, setttling undisturbed also settles heavier impurities in the crevices of of sub-soil regions.

Chemically, the purity is occurring due to the composition and desired reactions which occur. Like some spring or river waters bring utmost pristine- purity etc..

Bio-logically the cleansing keeps happening all the time in nature, creation of chlorine and process of chlorination occurs and chlorine is retained in moderate level

Hence the region which aids in recharge- regime for ground water- aquifers is the very source of pollutants- catch it in this stage. Even the foliage cover- leaves and others assist in cleansing/ purifying water. In the ancient vedic times, it is referred that neem, eucalyptus, papyras. pine cones etc.. provide the desired effects.

Also the charred- bone remains of after cremation rituals in water- bodies provide for carbon- remediation. There are studies of river waters remaining ever- fresh even after many years, as they have gone thu' the natural purification process. The marine life in the water-bodies are also noted to be in very good order.

It is the elements of nature which keep the water good and the man- made changes that causes the damages.

All these effects can be duly remedied - physically, chemically or bio-logically if a good assessment is done.

well wishes,

Ajit Seshadri  

the odor might have resulted from the distribution not the water itself. you need to check for decayed organics in the piping and the reservoir before you can be sure if the foul smell emanates from the water

Dear HM..

Your question asked 2years back has been answered well and all points covered.

Presently a comment has been made by @ Dr Falalu BH, indicating that the piping system and its integrity is to be judged for smell present in the g wtr.

It is indeed true that the pipes and its material need to be intact and in order

If the system is leaky, it is propable that the water could get contaminted from the matter getting into pipes and then into the water itself.

The ground water drawn from a sub-soil regime too could have been contaminated to induce smell.

Both these causes need to be addressed to make water free from odour etc.

The water is assessed for quality and then dealt with as required for remediation each by each on the contaminants assessed.

Well wishes.

In summer season water table decrease or water reached the very low level in this condition growth of various type of bacteria in water and those bacteria species produce the bad smell in water sources.