For decades the math was simple: treating process water to reuse standard cost more than buying fresh and paying to discharge. That math quietly broke sometime around 2023, and most plant operators haven’t re-run the numbers since.

Three curves crossed. Municipal discharge fees in US and EU industrial zones have risen an average of 9% annually for five years. Fresh-water industrial tariffs followed. Meanwhile membrane costs per cubic meter of daily capacity fell by roughly a third as manufacturing scaled.

A worked example from our own installed base: a beverage processor running 380 m³/day through an AquaPure WTX-500 recovers 88% of wash-down water at an all-in operating cost — membranes, CIP chemicals, power, amortization — of $0.61 per cubic meter. Their combined fresh-plus-discharge cost was $1.94. Payback landed at month 14, ahead of the 22-month projection, because discharge fees rose mid-contract.

The stranded asset now is the outfall pipe, not the treatment skid. If your last reuse feasibility study is older than your phone, it’s fiction.