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Rotten Egg Smell in Borehole Water: Causes and Treatment
- Rotten egg smell = hydrogen sulphide
- Only hot water smells? Check the water heater
- Low levels: activated carbon
- Higher levels: aerate, chlorinate or ozonate, then filter
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Find the Source
| Smell appears | Likely cause |
|---|---|
| In hot water only | A reaction in the water heater (its anode rod) |
| In hot and cold water | Hydrogen sulphide in the groundwater |
| Only from one tap or after water stands | Bacteria in pipes or a tank |
Treatment Options
| Method | How it works | Best for |
|---|---|---|
| Activated carbon | Adsorbs the gas | Low levels |
| Aeration | Air strips out the gas | Moderate levels in storage tanks |
| Chlorination + filtration | Oxidises sulphide; a filter removes the particles | Higher levels; also kills bacteria |
| Ozone | A strong oxidiser, leaves no chlorine taste | Commercial plants |
H-TECH Air-Cooled Ozone Generator RangeKSh 40,600
Carbon Block Coconut Shell Big Blue Cartridges (1um)KSh 1,300
Dosing Pump 2l/hKSh 23,000
948 FRP Tanks and PP FiltersKSh 13,500| Product | Price |
|---|---|
| H-TECH Air-Cooled Ozone Generator Range | KSh 40,600 |
| Carbon Block Coconut Shell Big Blue Cartridges (1um) | KSh 1,300 |
| Dosing Pump 2l/h | KSh 23,000 |
| 948 FRP Tanks and PP Filters | KSh 13,500 |
Current listed prices incl. VAT (updated 4 October 2026).
Related: chlorination, ozone generators, activated carbon.
Shock-Chlorinate the Well
When bacteria in the borehole or pipes cause the smell, shock chlorination of the well and plumbing often reduces it. The smell can return, so continuous treatment may still be needed.
Test Before Treating
Sulphur problems often come with iron and manganese, which need their own treatment (removing iron). A lab test lets us size the right system.
Watch: RO purifiers and water ATMs
Frequently asked questions
Why does my water smell like rotten eggs?
Usually hydrogen sulphide gas made by bacteria in groundwater, or a reaction in a hot water heater.
Is rotten egg smell water safe to drink?
The smell is mainly a nuisance at low levels, but test the water for bacteria and other problems before drinking it.
How do I remove hydrogen sulphide from water?
Carbon for low levels; aeration, chlorination or ozone followed by filtration for higher levels.
Why does only my hot water smell?
Often a reaction in the water heater; have the heater checked.