Är släckvatten en miljörisk vid bränder? : Möjlig påverkan på avloppsreningsverk, drickvatten, grundvatten och recipient i Stockholm.

Extinguishing water is formed when extinguishing fires. It contains fire residues, contaminants from what has burned and what has been used to extinguish with. When the fire is extinguished, the extinguishing water sometimes remains on the site and infiltrate the ground and flows on towards groundwater sources or into stormwater, sewage systems or nearby lakes. Materials such as electronics, furniture, solvents, chemicals and vehicles form environmentally hazardous pollutants in the event of a fire that can damage the surrounding aquatic environment and sewage treatment plants. The purpose of the report is to investigate how dangerous extinguishing water is for waste water treatment plants and recipients, what it contains and what volumes can be formed in the event of a fire. The report describes three fires and the pollutants analyzed in the extinguishing water from them, volumes of extinguishing water and how it may have affected the environment. Analyzes show that there are levels of metals, PAHs, PFAS, cyanide and surfactants in the extinguishing water. When comparing extinguishing water with limit values ​​and other waters, extinguishing water contains higher levels of pollutants than domestic water and is also above the limit for drinking water and surface water in many cases. Warning values ​​for wastewater are exceeded in some cases for metals. Toxicity analyzes show that the water contains substances that are toxic to aquatic organisms and humans.  Interviews with representatives from waterworks, the fire service, treatment plants and those who work with recipients around Stockholm show that they have methods for controlling pollution in treatment plants, drinking water and lakes. In the event of a fire, the fire brigade are careful with the amount of water and the use of foam. The fire brigade in Stockholm does not have routines or equipment for collecting large amounts of extinguishing water today. Preventive work by contacting and register companies where there is a risk of environmental impact in the event of an accident take place at treatment plants.  Impact on Henriksdals treatment plant, which is a big treatment plant, from these fires are low. Many pollutants bind to the sludge formed in the treatment processes, this reduces the impact on the biological purification step. However, there are toxic compounds left in the water that have an effect on the biological purification step, nitrification analyzes show. Calculations show that the extinguishing water´s addition of pollutants do not increase the levels in sludge and outgoing water significantly. Sludge is used as a soil improver and spread on fields, in this way the pollutants risk reaching recipients and groundwater in another ways. It may be better for a treatment plant to receive extinguishing water than to let the extinguishing water flow into a lake or water protections area, but treatment plants have the right to say no to extinguishing water. Suggestions for continued work in the area are to build on the experience of the fire water content and volumes used in firefighting. To work out a decision on who will bear the costs of disposing of extinguishing water when needed. A support function for the fire service would be needed that can be contacted when there are uncertainties of the risk of the fire water. The fire service could create a routine for how they could prepare collecting of firefighting water if needed.