We sample our customers’ wastewater to ensure that the sewer system and wastewater treatment processes work efficiently and to reduce environmental risks. Excessive pollution puts more load on wastewater treatment, increases the risk of blockages and breaches of environmental standards, and causes health problems. This is why we make sure that the quality of wastewater meets current standards.

The customer is responsible and may be charged a fee for pollution exceeding the permitted values if the concentration of pollutants in the wastewater exceeds the permitted limits. This charge will help to compensate for the harmful effects caused by wastewater that exceeds the standards, and to ensure the functioning of the treatment process and the public sewerage system.

Sewer problems on the customer’s premises must be rectified at the customer’s request and expense. If necessary, the customer can consult a specialist company to help solve problems related to sewers.

How is the fee for pollution exceeding limit values calculated?

  • Based on analyses of wastewater samples

A grab sample will be taken from the customer’s wastewater at no extra charge and if the concentration of any pollutant exceeds the limit value, a fee for pollution exceeding the limit values may be charged according to the pollutant group, see more here.

  • Billing period

The fee for pollution exceeding the limit values will be charged from the time of sampling until the next sampling, up to a maximum of six months.

  • Charging a fee for pollution exceeding limit values

If the initial sample shows excess pollution, we will give the customer the opportunity to rectify the situation before charging a fee for pollution exceeding the limit values. However, the fee may be charged following subsequent sample results.

The customer must monitor the composition of their wastewater and, if necessary, take measures to ensure that the wastewater complies with the rules approved by Tallinn City Council.

The fee for pollution exceeding the limit values is calculated based on the amount of water used during the billing period and according to the current prices for sewerage services.

PS From July 2026, we will use the average pollution levels of the last four samples to calculate the fee for pollution exceeding the limit values.

What causes wastewater pollution and how can it be avoided?

  • Acidity/alkalinity (pH)

Water that is too acidic or alkaline will damage sewer pipes and disrupt biological treatment processes. For this reason, industrial chemicals and highly acidic or alkaline substances must be kept out of sewers and, if necessary, neutralisation agents and systems must be used.

  • Suspended solids

Organic and inorganic solids often cause blockages (especially in combination with fat), increase the need for pump maintenance and put more load on the mechanical treatment stage at the wastewater treatment plant. Therefore, care must be taken to prevent excessive amounts of solid waste (e.g. food waste, soil, sand, plastic, etc.) from entering sewers. Where necessary, on-site pre-treatment, i.e. septic tanks or filtration and separation systems, must be in place and properly maintained.

  • Biochemical oxygen demand (BOD7)

A high level of BOD means that there is a lot of organic matter in the water that needs to be broken down. Excessive discharges of food waste, fats and other organic substances into sewers must therefore be avoided.

  • Chemical oxygen demand (COD)

COD measures the total organic matter that must be oxidised, including the part that cannot be broken down by biological processes. Minimizing the amount of chemicals, solvents and organic compounds discharged into sewers is therefore important.

  • Oil products

Oil products come mainly from industries and roads, often from cars and other machinery, causing significant environmental pollution and disrupting wastewater treatment processes. It is therefore important to use oil traps suitable for the flow rates, to keep vehicles well maintained and leak-proof, and to prevent oils and chemicals from reaching sewers or the roads (storm drains). In the event of a major spill, the Rescue Board and Tallinna Vesi must be informed, who will limit the spread of the spill and, if necessary, help clean it up.

  • Fats (cooking oils, resins, waxes, etc.)

Fats cause sewer blockages, disrupt biological treatment processes and increase the cost of wastewater treatment. This must be avoided by using grease traps and by avoiding pouring oil into sewers. Large quantities of waste fats must be taken to collection points accepting hazardous waste.

Grease traps used in restaurants require regular maintenance and cleaning. It is important to refill the grease trap with clean water immediately after emptying it. The grease trap must be of an adequate size, because the more grease or the smaller the trap, the more often it needs to be cleaned. In some cases, special bacteria can be used to reduce the amount of grease, but it should also be borne in mind that they require suitable growth conditions and time, and are not resistant to hot water and disinfectants.

  • Phosphorus (Ptotal) and nitrogen (Ntotal)

These come mainly from detergents, food waste and organic fertilisers and indicate excessive organic pollution. It is therefore important to use detergents that do not contain nitrogen or phosphorus and to avoid throwing food waste to sewers.

Let’s keep the Baltic Sea clean together!

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