We disinfect the well with a chlorine product whose dose we calculate from the water volume, and then pump the water out until the chlorine has been flushed away. Disinfection is included in well cleaning, which costs from €150. Tell us in the form why you want the well disinfected.
When well disinfection is needed
- After cleaning: during it, bacteria from the walls and bottom get into the water.
- After a repair, ring replacement or sealing of joints, when people with tools have worked in the well.
- After flooding: floodwater or rainwater that has run in through the lid or joints carries soil, fertiliser and bacteria with it.
- If an animal or bird has fallen into the well.
- If a laboratory water test has found coliforms, E. coli or intestinal enterococci.
- For a new well before the water is used.
Disinfection does not change the chemical composition of the water. It does not reduce iron, manganese, nitrates or hardness. If these values are high in the water test, the solution is water treatment or a change of water source, not chlorine.
Why disinfection without cleaning rarely helps
Bacteria live in the silt at the bottom and in the coating on the walls. Chlorine acts on the water and surfaces, but it only partly penetrates a silt layer, and soon after chlorination the bacteria multiply again. So a well with silt in it is cleaned first and only then disinfected. Disinfecting without cleaning makes sense only for a clean well, for example after minor repairs or brief flooding.
How we disinfect a well
- Calculation We measure the ring diameter and the height of the water column. In a well one metre in diameter, each metre of water is about 0.79 m³, so two metres of water is about 1.6 m³. From this we calculate the amount of product.
- Treating the walls We spray the ring walls with chlorine solution from the water level to the top, including the underside of the lid, because bacteria often remain there where the water does not reach.
- Chlorinating the water We mix the product into the well water and, if the well has a pump, run the water through the system to the taps, to disinfect the pipes too.
- Contact time We leave the well closed for a time set by the product and the dose. During this time the water is not used.
- Flushing We pump the water out and lead it away from the well and garden beds until the chlorine smell can no longer be noticed. We let the well refill with fresh water.
- Control test Once the chlorine has been flushed out and the well pumped out several times, we take a sample for microbiological testing at an accredited laboratory.
Household bleach and cleaning products with fragrances and surfactants are not suitable for a well: they leave a taste and substances in the water that have no place in drinking water. We use products intended for drinking water disinfection.
What the water test shows after disinfection
In a microbiological water test the key indicators are E. coli, intestinal enterococci and coliforms. In the drinking water regulation the limit value for all three is 0 CFU/100 ml. For a private well this regulation is not mandatory, but the laboratory result is compared directly against these values.
| Result | What it means | What we do |
|---|---|---|
| All three 0 | The disinfection has worked | Use the well; next water test once a year or after flooding |
| Coliforms, but E. coli 0 | Surface water or soil is getting into the well | We look for the route: the lid, the top ring joint, the ground around the well |
| E. coli or enterococci | Faecal contamination: sewer, toilet, manure | Do not drink the water; we look for the source, then repeat cleaning and disinfection |
Cabinet Regulation No. 547 of 26.09.2023 on drinking water, Annex 1: E. coli, intestinal enterococci and coliforms 0 CFU/100 ml; sub-point 4.5: the regulation does not apply to individual supply points used by fewer than 50 persons or where extraction does not exceed an average of 10 m³ per day. Source: likumi.lv, checked 03.11.2026.
If coliforms come back
If bacteria show up in the water test again after proper cleaning and disinfection, there is no point repeating disinfection over and over: the contamination is coming from outside. The most common routes are leaky ring joints, a lid without a seal, a top ring too low above the ground and a slope that sends rainwater towards the well instead of away from it. These are fixed by well repair and well top and cover.
If the well is lower than a septic tank, toilet or manure heap, the cause may be there. State regulations set no minimum distance between your own well and a septic tank, so we assess each case on site: the terrain, the soil and the direction the groundwater flows. If the source cannot be removed, a permanent solution is UV water disinfection on the house water supply.
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. Source: likumi.lv, checked 03.11.2026.
How much well disinfection costs
Well cleaning together with disinfection costs from €150, and that is the most common case. If the well is clean and only disinfection is needed, we name the price based on the water volume, the well depth and whether the pipes and pressure tank need disinfecting too. A microbiological control test can be ordered together with the work: basic water test from €35, full test from €95. All prices: prices.