Estonian Waterworks Association EVEL arranged training event for local waterworks 10 – 11 May, 2018 in Tartu, Estonia. The topic of the event was cooperation with industrial customers, post treatment of waste water in treatment plans, and also possibilities for pretreatment of waste water already at the industries. Tallinn University of Technology TUT presented their pilot treatment device for removing phosphorus and hazardous substances from waste water, which is in test use at Tartu waste water treatment plant WWTP. In workshops, themes were cooperation and the terms of connection with mutual benefit for both WWTP and industry, and in the other hand, hazardous substances in the industrial waste water treated at municipal treatment plants. The outcome of workshops strongly brought forward the need of WWTPs to know what kind of hazardous substances the industry will discharge to WWTP already when negotiating contracts. Workshop discussions also brought up contradicting laws and regulations especially for effluent limit values, and the need for legislation changes.