There is a Rotten-Egg Smell (Hydrogen Sulphide)
If there is a smell from the water in a private well supply it is almost certain to be Hydrogen Sulphide (H2S) especially if it has a rotten-egg smell.
If the Hydrogen Sulphide originates at your well, or somewhere after your well; chlorinating your well, simply by pouring chlorine or some other sterilising agent like bleach down the well, often solves the problem. Add a bottle of domestic bleach to several gallons of water, and pour it down the well, this may well solve the problem permanently.
However, if the source of the Hydrogen Sulphide occurs somewhere before your well, then chlorination will not solve the problem.
There is a Smell from the Hot Water, but not the Cold
Many water heaters have an electrode with a positive charge, often referred to as an “anode rod” which produce excess ions that wear off the anode rod and adhere to the inside wall of the water heater, forming a protective layer, preventing it from corroding. Sometimes they are made from a magnesium type material this can chemically produce Hydrogen Sulphide from naturally occurring sulphates dissolved in the water. This problem can be easily solved.
It is also possible, but less likely, that bacteria (sulphur reducing bacteria) have contaminated the heating system and that they are producing Hydrogen Sulphide from the sulphates in the water. If this is the cause of the problem, the solution is to add a couple of cups of bleach to the water feeding the heater. Let the hot water run from all the hot water taps until you smell the bleach. Let the water sit throughout the system for a few hours. If the problem is caused by bacteria, this will certainly eliminate it.
The smell could also be as a result of some animal, especially a rodent, falling into the storage tank. A bacteria analysis would confirm if this is the case.
There is Ammonia in the water
The level of Ammonia in ground water is normally below 0.30mg/l. and at that level it is not a problem. Higher natural levels of up to 3mg/l can be found where there are layers of rock rich in humic constituents, similar to those found in boggy areas. Surface waters may also contain high levels. The presence of ammonia in water at levels higher than 0.30 mg/l are an important indicator suggesting that there may be harmful bacteria (faecal coliforms) present in the water, in this case it might be a good idea to have the water checked for bacteria.
Other problems include:-