The use of geothermal water is becoming more and more popular for technological applications. But before this application water must be treated. Iron compounds cause precipitation of technical devices, which in turn reduces their efficiency. That is why we need to know how high temperatures and salinity effect water treatment. This paper determines the effectiveness of the iron removal process using four methods: aeration, aeration and filtration, aeration with coagulation, and coagulation, which were measured experimentally. The paper presents a procedure to optimize the coagulant dose and method of preparation of water model. Efficiency of iron removal was measured by the total iron concentration in raw and treated water model. It was shown that the effect of coagulation was the best method of iron removal with effectiveness up to 98-99.5%. Iron removal decreases with increasing salinity. Higher temperatures do not affect the process of iron removal in water.