( ( ( ( ( ( At most ) ( , ( ( your sterilizer ) ( can ( kill ( ( some water ) ( born pathogens ) ) ) ) ) ) ) , ) but ) ( ( total sterilization ) ( ( is not ) ( ( possible or ) desirable ) ) ) ) . )
(ROOT (S (S (ADVP (IN At) (RBS most)) (, ,) (NP (PRP$ your) (NN sterilizer)) (VP (MD can) (VP (VB kill) (NP (NP (DT some) (NN water)) (VP (VBN born) (NP (NNS pathogens))))))) (, ,) (CC but) (S (NP (JJ total) (NN sterilization)) (VP (VBZ is) (RB not) (ADJP (JJ possible) (CC or) (JJ desirable)))) (. .)))
At most, your sterilizer can kill some water born pathogens, but total sterilization is not possible or desirable.
(ROOT (S (NP (NNP Water)) (VP (MD can) (VP (VB be) (VP (VBN boiled) (S (VP (TO to) (VP (VB kill) (NP (NP (NN giardia)) (CC and) (NP (RBS most) (JJ other) (NNS pathogens))))))))) (. .)))