Abstract: A system (11) for providing purified water comprises a plurality of individual modules, each of which includes a separable head (13) and a canister (17), which modules are joined one to another via these heads to create a composite manifold (15). The heads and canisters are respectively of substantially identical construction, and the hollow canisters include the following units: preheater, prefilter (25), pump (27), membrane purification (29), postfilter (31), and UV treatment. The overall system is monitored by a control unit (131) that is regularly interrogated by an off-site, headquarters computer, and both the control unit (131) and the headquarters computer are proactive in detecting potential difficulties that may be able to be readily remedied by promptly dispatching a serviceperson with a replacement for the canister containing the operating unit that requires replacement.