A method for remediation of water from small biological wastewater treatment plants SBWTPs, wherein municipal wastewater from households is first partially purified in a SBWTP to contain in an outflow from the SBWTP the maximum permissible values of inorganic pollutants: ammonium ion (NH 4 +) ≤ 40 mg / L, nitrate (NO 3 -) ≤ 20 mg / L, nitrite (NO 2 -) ≤ 1.0 mg / L, sulphate (SO 4 2-) ≤ 30 mg / L, phosphate (PO 4 2-) ≤ 10 mg / L; the highest average annual microbial content: Escherichia coli ≤ 130,000 MPN / 100 mL, intestinal enterococci ≤ 250,00 MPN / 100 mL, Clostridium perfringens ≤ 850 CFU / 100 mL, coliform bacteria ≤ 700,000 MPN / 100 mL; the chemical oxygen demand is ≤ 150 mg O 2 / L, the biochemical oxygen demand (BOD 5) is ≤ 30 mg O 2 / L; the conductivity measured at 20 ° C is ≤ 9000 μS / cm, characterized in that the method includes the following steps: i) nano-remediation, where a suspension of zero valent Fe 0 particles nZVI is added to the partly purified water brought directly from the SBWTP to a reactor, wherein the concentration of nZVI in the water is ≥ 0.25 and ≤2 g / L, the individual nZVI particle has a specific surface area of at least 25 m 2 / g, its average size does not exceed 80 nm and a weight fraction of nZVI in the suspension is 20 % and the nanoparticles contain at least 80 wt. % of the reactive Fe 0 component, followed by mixing for a duration of ≥ 6 and ≤ 10 hours and then settling of a slurry containing nZVI with bound inorganic, organic and microbiological pollutants for a duration of ≥ 3 and ≤ 10 hours, whereby the slurry is being separated from the water and taken to a container and whereby partially purified water is fed to a further reactor; ii) purification with a solution of oxidants based on a hypochlorous acid or an iron salt in six-valent form, wherein at least one oxidant is added to the partially remediated water from step i) which still contains a concentration of nZVI ≤10 mg / L and the water is retained in the reactor at least one hour after the addition of the oxidant to the reactor, whereby the remaining organic pollutants being oxidatively decomposed, suspended pollutants coagulate, water is disinfected, so the value for the microbiological pollutants Escherichia coli, intestinal enterococci, and coliform bacteria is equal to 0 MPN / 100 mL and the value for Clostridium perfringens is 0 CFU / 100 mL; iii) purification of water from step ii) by ion exchange, wherein the water is led through at least one layer of a cation exchanger and through at least one layer of an anion exchanger; iv) filtration of water from step iii) carried out by passing water through at least one layer of activated carbon including granular activated carbon, wherein in step iii) and step iv) the residual dissolved pollutants and fine suspended particles are removed from the water. i) nano-remediation, where a suspension of zero valent Fe 0 particles nZVI is added to the partly purified water brought directly from the SBWTP to a reactor, wherein the concentration of nZVI in the water is ≥ 0.25 and ≤2 g / L, the individual nZVI particle has a specific surface area of at least 25 m 2 / g, its average size does not exceed 80 nm and a weight fraction of nZVI in the suspension is 20 % and the nanoparticles contain at least 80 wt. % of the reactive Fe 0 component, followed by mixing for a duration of ≥ 6 and ≤ 10 hours and then settling of a slurry containing nZVI with bound inorganic, organic and microbiological pollutants for a duration of ≥ 3 and ≤ 10 hours, whereby the slurry is being separated from the water and taken to a container and whereby partially purified water is fed to a further reactor; ii) purification with a solution of oxidants based on a hypochlorous acid or an iron salt in six-valent form, wherein at least one oxidant is added to the partially remediated water from step i) which still contains a concentration of nZVI ≤10 mg / L and the water is retained in the reactor at least one hour after the addition of the oxidant to the reactor, whereby the remaining organic pollutants being oxidatively decomposed, suspended pollutants coagulate, water is disinfected, so the value for the microbiological pollutants Escherichia coli, intestinal enterococci, and coliform bacteria is equal to 0 MPN / 100 mL and the value for Clostridium perfringens is 0 CFU / 100 mL; iii) purification of water from step ii) by ion exchange, wherein the water is led through at least one layer of a cation exchanger and through at least one layer of an anion exchanger; iv) filtration of water from step iii) carried out by passing water through at least one layer of activated carbon including granular activated carbon,