The smell itself tells you a lot: a silt and rot smell comes from the well, a rotten egg smell usually from the aquifer or the water heater, and a sewage smell means contamination that has to be found. First find out where the smell arises, then do a water test, and only then choose a solution. We take a sample, clean and disinfect the well (from €150), and recommend treatment if the fault is in the water, not the well.
First: where the smell arises
Compare three samples: water taken straight from the well with a bucket, cold water from the tap and hot water from the tap. This simple test often shows straight away whether the problem is in the well or in the house system.
- Only the hot water smells: the fault is usually in the water heater, where the magnesium anode reacts with sulphates in the water and produces hydrogen sulphide. The well is not to blame here, and replacing the anode or servicing the heater helps.
- The tap water smells, but the water from the bucket does not: the smell arises in the pipes, pressure tank or filters, where water stands for a long time. Check the filter cartridges and water filter maintenance.
- The water from the well already smells: the cause is in the well or the aquifer, and it is then identified by the type of smell.
What each smell means
| Smell | Most common cause | What to do |
|---|---|---|
| Silt, swamp, rot, mould | Organic deposits at the bottom, fallen leaves, a rotting wooden lid or ladder in the well, algae if light gets into the well | Well cleaning and disinfection, lid replacement |
| Rotten eggs (hydrogen sulphide) | Hydrogen sulphide from the aquifer itself | Water test and treatment: aeration or a filter |
| Sewage, manure | Wastewater or manure gets into the well through the ground or surface water | Do not drink the water, microbiological and chemical water test, find the source |
| Metal, rust | Iron and manganese in the water | Water test and iron removal |
| Chlorine | Recent disinfection | Pump out until the smell is gone |
| Petrol, oil, solvents | A fuel or chemical leak nearby | Do not use the water, test for petroleum products, find the leak |
With hydrogen sulphide there is usually no point cleaning the well, because the gas comes with the groundwater. On solutions: rotten egg smell in water. A silt and rot smell is exactly the case where well cleaning helps: after removing the silt, cleaning the walls and disinfecting, the smell usually goes.
Sewage smell in well water: what to do straight away
If the well water smells of sewage or manure, stop drinking it and using it for cooking until you know the water test result. The smell means wastewater or manure is getting into the water, and bacteria usually get in with them.
- The water test should check E. coli, coliforms, ammonium, nitrites and nitrates: they show whether the contamination is fresh or long-standing.
- Check what lies higher than the well: a septic tank, holding tank, toilet, compost, barn, the neighbours' systems.
- Check that rainwater from the yard does not run towards the well and that the top ring is high enough above the ground.
- Cleaning and chlorine alone do not remove the contamination: if the source remains, the smell and bacteria come back.
State regulations set no minimum distance between your own well and a septic tank, and no protection zone is set around a private well if wastewater infiltration has been prevented. This means the responsibility lies with the owner: the well and septic tank are placed so that wastewater cannot get into the well. More detail: protection zone around a well.
The Protection Zone Law, Section 9, paragraph two: no protection zones are set for boreholes, wells and springs that individuals use for their own needs, if the site has been landscaped and wastewater infiltration and water pollution have been prevented. We found no national distance standard between a well and a septic tank in Cabinet Regulation No. 384, LBN 222-15 or LBN 223-15. Source: likumi.lv, checked 03.11.2026.
What the water test shows
The drinking water regulation sets no numerical limit for odour: it must be acceptable to consumers and show no abnormal change. So the cause of a smell is identified by other indicators, which the laboratory compares with the regulation's limit values:
| Indicator | Comparison value | What it indicates |
|---|---|---|
| E. coli, coliforms | 0 CFU/100 ml | Faecal or surface water contamination |
| Ammonium | 0.50 mg/l | Fresh organic contamination or the natural composition of the aquifer |
| Nitrites | 0.50 mg/l | Contamination that is still breaking down |
| Nitrates | 50 mg/l | Long-term influence of manure, fertiliser or wastewater |
| Iron, manganese | 200 µg/l, 50 µg/l | Metallic taste, deposits, colour |
We take the sample ourselves, deliver it to an accredited laboratory and explain the result: basic water test from €35, full test with microbiology from €95. How to prepare for the sample: well water testing.
Cabinet Regulation No. 547 of 26.09.2023 on drinking water, Annex 1: E. coli and coliforms 0 CFU/100 ml, ammonium 0.50 mg/l, nitrites 0.50 mg/l, nitrates 50 mg/l, iron 200 µg/l, manganese 50 µg/l; odour: acceptable to consumers and no abnormal change. For a private well the regulation is not mandatory (sub-point 4.5), and the values are used for comparison. Source: likumi.lv, checked 03.11.2026.
How much getting rid of the smell costs
If the smell is caused by silt and deposits, well cleaning with disinfection costs from €150. Lid replacement or putting the top ring in order is agreed after inspection. If the fault is in the water composition, the price is set by the treatment equipment we choose after the water test. All prices: prices.