Hi Bojan. Seems you have ...
Published by Edward Erasmus, Air,surface,water sanitation equipment manufacturer and consultant.STOP TB
Hi Bojan. Seems you have received many correct answers below.
If possible filtration is the best way to reduce organic matter that acts as a food source for bacteria. Water is also seasonal so the analysis you have now could change in future but regardless is important.
After filtration you could look at a storage tank for the water and place a UV-C light in the tank. The problems with inline UV-C is that the lamp needs 15-20 min to heat up and have enough UV-C emitted on the passing water.Always remember that about 1/3 of the wattage is UV-C and wear protective eyeware.
www.ozoneuv.co.za offers many chemical free water sanitation methods.
Please see attached spec sheet on the Sani Submersible UV-C