If you have to deal with very silty /dirty water, I would recommend looking at some sort of pre filter. I use an ex Brit Army Millbag, which is essentially a tightly woven canvas bag you fill with dirty water and catch the cleaner stuff that trickles out..

Its very lost tech, but works very well. They are now available on the civilian market and tests carried out by the maker show that not only do they reduce the particulate load, but they also reduce biological contamination. I don't recall the exact figures or whether it was bacteria and /or virus, but it did offer an unexpected but worth while reduction, taking some of the load off your main filter..


Men of Harlech[Linked Image]