The above analysis of the steady state flux of pure water across BW30 did not consider membrane fouling effects which may lead to a considerable reduction in 𝐽 !,#$%('') over time. !,#$% , over time, calculated from three independent preconditioning datasets. Error bars in 𝐽 ̅ !,#$% represent standard errors of the mean (cf. Section S4, Eq. S3).