A subsea water processing system and associated methods are disclosed. The subsea water processing system includes a microfiltration unit, an ultrafiltration unit, and an electrochemical unit. The microfiltration unit includes an oil-tolerant microfiltration membrane and is configured to receive a stream of produced water and to produce a first treated stream of water. The ultrafiltration unit is fluidly connected downstream of the microfiltration unit, includes an oil-rejecting ultrafiltration membrane, and is configured to receive the first treated stream of water and to produce a second treated stream of water. The electrochemical unit is fluidly connected to at least one of the microfiltration unit or the ultrafiltration unit, and is configured to produce an acid and a base, and to deliver the acid, the base, or both the acid and the base to the at least one of the microfiltration unit or the ultrafiltration unit during a cleaning cycle.