A method for reducing content of perfluoroalkyl and polyfluoroalkyl substances (PFAS) in PFAS-contaminated water from the environment, comprising the steps S0) Subjecting PFAS-contaminated water collected from the environment to a purification step to obtain a first water stream (Wred1) having a reduced content of PFAS and a second water stream having an increased content of PFAS; S1) Feeding the water stream having an increased content of PFAS into an apparatus for reducing content of perfluoroalkyl and polyfluoroalkyl substances (PFAS) in PFAS-contaminated water, the apparatus comprising: a reservoir for accommodating PFAS-contaminated water, the reservoir having a longitudinal extension between a top end and a bottom end; at least one gas injection device arranged at least partly inside the reservoir to inject gas into the water and thereby create a foam containing PFAS at the water surface; and a collection container arranged in fluid communication with the top end of the reservoir to collect the foam; wherein the reservoir comprises a water inlet for supply of PFAS-contaminated water, and a water outlet arranged at the bottom end for discharging water with reduced PFAS content (W red2), said feeding being such as to achieve a water level above the gas injection device(s); S2) Injecting gas through said gas injection device to thereby create the foam containing PFAS at the water surface and allowing said foam to exit the reservoir to the collection container; S3) Collecting the PFAS-containing foam in the collection container; S4) Removing water (Wred2) with reduced PFAS-content from the reservoir through the water outlet; S5) Combining the first water stream (Wred1) and the water (Wred2) obtained in step S4); and S6) Releasing the combined water streams obtained in step S5) to the environment. S0) Subjecting PFAS-contaminated water collected from the environment to a purification step to obtain a first water stream (Wred1) having a reduced content of PFAS and a second water stream having an increased content of PFAS; S1) Feeding the water stream having an increased content of PFAS into an apparatus for reducing content of perfluoroalkyl and polyfluoroalkyl substances (PFAS) in PFAS-contaminated water, the apparatus comprising: a reservoir for accommodating PFAS-contaminated water, the reservoir having a longitudinal extension between a top end and a bottom end; at least one gas injection device arranged at least partly inside the reservoir to inject gas into the water and thereby create a foam containing PFAS at the water surface; and a collection container arranged in fluid communication with the top end of the reservoir to collect the foam; wherein the reservoir comprises a water inlet for supply of PFAS-contaminated water, and a water outlet arranged at the bottom end for discharging water with reduced PFAS content (W red2), said feeding being such as to achieve a water level above the gas injection device(s); S2) Injecting gas through said gas injection device to thereby create the foam containing PFAS at the water surface and allowing said foam to exit the reservoir to the collection container; S3) Collecting the PFAS-containing foam in the collection container; S4) Removing water (Wred2) with reduced PFAS-content from the reservoir through the water outlet; S5) Combining the first water stream (Wred1) and the water (Wred2) obtained in step S4); and S6) Releasing the combined water streams obtained in step S5) to the environment.